 Thank you very much. Good afternoon, as Professor Maria Calvo presented me. I am coming from Klujnapoka, Romania. And today I will present some aspects about optical lithography, basics, and practice. Coming from Romania, it's difficult. May I speak standing on the stairs, because it's better. So I'm coming from Romania. It's a country from Europe, a little bit closer to Italy. So at the border with Hungary. And we are living in Klujnapoka, which is a big town in the northern part of our country. It's a big university center. Also, we have a lot of research institutes. And we are working in the National Institute for Research and Development for isotopes. Here is located our institute. You can see a few buildings, which represents each of them, the department of one big topic for research. We have five main directions. It's a mass spectrometry, chromatography, and applied physics. We have physics of nanostructure systems. We have isotopic physics and technology, a center of a new department, center of research and advanced technologies for alternative energies, where it is located, the center for electronic scanning and transmission microscopy. And it's molecular and biomolecular physics, where I'm activating, I belong to this department. More information about it, you can find on our site. And there you can find also a brochure about the activity of our groups and also about the services we are able to do for different customers. So, I am part of the faculty. I'm here to do for different customers. So, I am part of the femtosecond laser laboratory. You can see here the laser lab in the central part is the femtosecond laser, it's at 10-13 nanometers, almost 200 femtosecond part duration and 80 kilohertz repetition rates. And also it's connected with two spectrometers. This is one for, this is time-resolved fluorescence and here is transient absorption. And also is the microscope, which is connected with the laser and it allowed us to create some structure. These are done, everything I show here is done in our lab. So, for today, I will go a little bit deeper in the optical lithography and I will try to create some reasons for the people who didn't start to work in this field to take a look or just take a look or more to try to start research in this field. Why should we work in such a field is the large number of applications for optical limiting. We all want to reduce and decrease the size of structures to miniaturize everything to be able to carry on with us everywhere. Also for fluorescence imaging, which is really useful, but also is a micro fabrication, as Professor Colin Shepard said. Major part of confocal microscopes are acquisited by industry. It's about the micro-electronic industry and also for 3D data storage, which is really important to keep the data. What offers the, let's say, I would like to go more to the metallic construction of the structures and in this way I can have some advantages because when I create small structures, I create larger surfaces than I have on a plain surface when I have gold, metallic gold deposited on a glass cover plate. And also I have the localized surface plasma resonance, which is not possible to have it on that flat, atomically flat surface, never. So also why to have them arranged in different shapes. First, why to have noble metals. We have oxidation proof for gold especially, but we can use silver and cover with gold and in this way you have better conductivity properties and oxidation proof. We have tunable sizes, geometries. We have the compatibility with biomolecules. We can create electrodes for electrochemistry and we can decrease the size and in this way we can detect traces of substances. It's really interesting to work with interdigitated electrodes, which varies their properties function on the distance between the fingers and function of the width of the fingers. And last but not least, they can be support for substrate, which is really important not to use all the time solutions. Now, I will talk about lithography, some things about origin and key stages, about direct laser writing in polymerization and metallic structuring in thin films. Some things about optical microscopy and characterization. The origin of the lithography is in the ancient Greek. From lithos meaning stone and graphite, which is to write, we can realize that it's about to write on a stone. And now, if you have time to visit Berlin or other towns in the world, if you visit Dali Museum at the entrance, you may watch a very interesting film about lithography. It's lithography in art. And if you are careful and you have patience enough, you can discover very nice how to create some piece of art at home in a very smart way. And Dali created masterpieces in this way using the lithography technique. So, we have two stones. It's a white one surface and the black one. And you can use these surfaces to create first a picture on the white one. Then you put some talc powder. Then you put some gum arabic. You spread them nice. Then this is a first step and you have a smooth surface. And then you are coming on the black stone where you have graphite. You have a cylinder and you move it back and forth several times and you go back to the white surface. I forgot to say something. When you draw on that white surface, you have to use a grey crayon or an Indian ink which contains some oil. So, in this way you create some distinguished areas where you have a grey and you have a normal surface. Then you are coming with acid and water. You pour them on the surface, spread it again and then you are coming and wash with water for several times until everything what is out of that picture you made it at the beginning with your ink disappears. So, you receive a kind of a map. Then you are coming with the piece of paper. You light on the surface, then rule back and forth another cylinder and take and you have the picture. So, this was invented by Alois Senefelder which was a German author and actor and it was a cheap way to print his theoretical work. So, why I presented this story which is long because everything what we are doing in lithography doesn't matter which technique we use follows somehow these steps because there are some steps in the lithography and we create with different, let's say, chisel which is a carving tool. We can create some pictures. If we use acid and water, we have the etching process and if we consider the light or a laser beam as optical chisel we can create the optical lithography. So, now we may do this in two different ways. We can use some masks and it was really helpful. The course we have before, if we have a mask we have to follow some steps before. This is first a resist preparation, developing, patterning, deposition or etching, resist removal and then we arrive to the patterned structures but we can also to have a direct rate of materials using microscopes or other optical setups. We can have the direct obtaining of patterned structures or post-processing, baking and then developing and obtaining these structures. In this process we can identify three main stages is the substrate preparation which means we have to create that smooth surface about I spoke in the story. That means we can deposit a droplet onto the cover plate or we can add thin films. Then we have the optical process itself and finally we have to develop these structures is the second part of my story and characterization of the patterned structures using optical microscopy, SEM, TM or atomical force microscopy. For the film preparation we can use a spin-coater technique. Here is the equipment, the spin-coater and here we can see that first of all we have to make a setting of the parameters, the speed, the acceleration and the time and here you can see I put five steps. It's very important when you deposit I will go further because when I place the cover plate on the chuck on the holder and then I hold the vacuum to keep very well the plate during the spinning move we can see here that after deposition of the droplet on the substrate, the glass substrate or what substrate we want we can see here the droplet. It's really very important to take into account the wetability of the mixture with the pour on the surface because if we don't care about hydrophilicity and hydrophobicity of the surface we are not able to have a complete covering of the surface and the quality of the film is not too good for us. So in this idea it's good to plan to have several steps at the beginning with slower motion to allow the droplet to be flattened and to cover in a good manner the surface because at a moment when we start the holder to rotate to be able to spread uniformly the material on the surface. Okay, the first step is the position of the solution on the substrate then we have we don't have we have the spinning of the substrate and we have the centrifugal forces which action about among the droplet and we can see here that the solution is expolded at the margins and during the rotation we have a competition between the centrifugal forces and the viscosity forces a part of the material wants to leave the substrate but viscosity till tends to keep the material on the surface and in this way we reach to create at the beginning in the center a thinner layer and then in the follow steps we can see that our substrate starts to be more uniformly and continuing the movement you can see here that the layer becomes thinner and thinner but we have somewhere in the center lower thickness and we have at the margins the edge effect the thickness of the final layer depends on the thickness of the initial layer of course is about function of the amount of solution deposited, the rotation speed, the viscosity and everything is here rotation time and liquid density everything was studied in very good conditions and there is a very strong reason because when you are starting to ride to do lithography to focus in fact in a thin layer if you don't have the same thickness you will have out of focus in the part of the film where the thickness is not uniform and you may have bad shapes of your structures the last one, the last step is about the evaporation I will go back, you can see here it was about the the thickness of the layer and then we have the evaporation, so it's a viscous flow and evaporation, two steps which are going together but first appear a little bit earlier and the second evaporation is responsible for creation of a layer which has a high viscosity and the appearance is as somehow the solution deposited is frozen on the surface so it cannot move anymore and you can work on it in very good condition and this is due to higher increase of the viscosity ok, what we can obtain at the end of the process if we have a transparent solution based on polymer, polymer docked with some metallic salts, we can see here nice round circle sometimes and here is on a gold layer deposited on the glass surface sometimes it's not necessary to use a large amount of substance because first of all we are working many times with very expensive substances and due to that edge effect we cannot use in proper condition particularly in the center, in that part of the film where we are sure that we have uniform thickness, so it's no use to spread a lot of material just to fill in the surface and not use it this is a practical advice because I'm doing, so now taking into account that for the optical lithography express my intention to go through direct writing of the material I will present here a few things about the laser regime used for this direct writing and in this in this view I present here the situation when we use UV laser beam and when we use near infrared femtosecond laser beam we can see two different behaviors is one photon absorption and two photon absorption this is function of the materials we use monomers or oligomers and the molecules specific which are capable to absorb at one photon or two photon now some reasons for these two photon absorption at a moment, it's about 1931, theoretically was predicted that even some molecules are not able to absorb normally at a given wavelength if they absorb simultaneously two photons with the same energy and having a lower energy from infrared they are capable to to be excited and this is possible when they are irradiated with a large density of photons now nowadays it's not necessary to use extensively this because they are a lot of molecules smart molecules meaning that we have large extended conjugation they are some type push-pull molecules you can imagine a chain and you have at the end of the chain withdraw a group and at the other side you have a pushing group so you have a large conjugation and the properties are very good and in this way because you use the exciting of the molecules from HOMO you create that excited states and in this way the energetical gap you need for irradiation of the system is decreasing considerably because you already have a component excited state and in this way when this component will go on the fundamental state will give the energy and will save a lot of energy and efforts to do what before was doing without this type of molecules if there are some questions during the presentation please stop me and put not extend because we have to be in time but if there is something unclear please ask now I will focus a little bit on two-photon optical lithography in polymer I took an example when it is used the advantage about I talked before meaning that we can use an excited state of a component to hit another component and this to allow the monomer to be polymerized so we need in the system to have free radicals which start the reaction and in this way we have to create them in a very smart way here Farsari and her team used a multifunctional ligand you can see here an esteric group and double carbon-carbon double bond as a multifunctional ligand and this is the eosin why a sensitizer dye and this is the two-photon present to photon absorption in infrared and after this is excited then this amine which is additionally put in the system is oxidized by a triplet state because amine has a pair of lone electrons and it is possible to be oxidized meaning that oxidize is turning from fundamental state in an excited state so this then will attack this monomer and will start the polymerization we can see here the visible spectrum of eosin and also here is a comparison with two different dyes is about the same dye eosin and rose bengal and you can see the same spectrum but also you can see the behavior into photon absorption so this range of absorption in one photon allows to situate its absorption into photon windows for the laser and in this way we can have photopolymerization we can see in the next slide using a laser at 1028 nanometer femtosecond laser with this characteristic to impress molecules which are sensitive in the green range so what we can see here for example here is the femtosecond laser and here we have a beam splitter and the power meter which records during the process the power and then we send the laser beam through a mirror, a shutter and neutral density filters in the objectives and this objective is we will focus the laser beam in our sample which is placed on a piezo system is just a Z-translator and here you can see a detail meaning that we have the sample put with a droplet in the bottom part and we go okay, I'm sorry I say we because I did something so I didn't but it is the way to do it is focusing here at the top of the droplet and then the written process is doing to the top to the bottom and finally the final step is the glass slide interface with the droplet and it is really important when we arrive there to have a very good attention between the droplet and the substrate and also it is really important to take into account these resolutions, we have a lateral resolution calculated function of the wavelength and numerical aperture but we have also an axial resolution and in condition they use for slicing one microns between layers it is really smart because the axial resolution is 3.2 which is larger than the distance between the layers and in this way they ensure that the structure will be bind on the surface because then you are taking and you want to develop it and if you don't stick very well on the surface you will lose everything even a day for work perhaps sometimes very expensive substances okay here are the results you can see here that the image is distorted and this is due to the polymer shrinkage and I just explain the problem with the actual resolution and here this micro gear is also with the same distortion here it is possible to see that the resolution is around one micron which is the lateral resolution and the calculated for accuracy was a little bit lower so in this situation the source of error was that they use monomer instead using an oligomer and they needed for this to use a larger amount of initiators and when you have a large amount of initiators for photopolymerization which is a chemical process it's really difficult to stop the process you cannot keep under control and the way you can control it is to decrease the concentration of the initiator so as time as they use monomer they needed a lot of initiator to create the voxels and to have the structures so using oligomer you have larger chains and in this way you can construct with less amount of initiator or the structures so now another type of polymerization process but using for this time an inverted configuration and here is really very nice depicted that when you use femtosecond laser or near infrared laser you have a low energy and the reaction takes place exclusively in the focal point in that small volume which allows to create 3D objects because you can penetrate the entire block of the resonance without damaging changing the refractive index sorry I should have to yes without changing the refractive index and in this way you have efficiency you can create the right shape you want and finally in the last step when you have to develop all these structures you can receive nice pattern structure we are speaking here about voxel and that voxel is a very small entities where appear a different material the polymer which has a different refractive index from the clear liquid it is used at the starting of the process so it is really easy as in the previous experiment to identify if there is something change in your system because having different refractive indexes in the first experiment it was some galvanometric mirrors they can detect these changes you can see here the droplet the resin then is the irradiation of the droplet through the objective we have here the voxel appear exactly at the focal point under the 3D stage sometimes for practical purposes the droplet is pre-baked for given time and temperature and the same thing is done at the end of the process in the same parameters to be sure that they receive the good structure so it is a dissolution and the result which can be seen here you are using a 20 second laser to allow just a small area for absorption and your objective limit resolution of your system I mean if you use a simple laser for example just one photon absorption is the resolution is different from they have the same resolution it was presented before lunch it was quite at the end and it was presented the behavior when you have the confocal microscopy and you have the pinhole and you send the light and you let just part of the light from the object to cross the pinhole and in this situation first of all with UV beam I jumped but I will have some slides later the disadvantage of one photon absorption is that when you irradiate it's okay so you have resolution you have nice things but you irradiate as a column you impress the entire material and you do the path of the laser beam so sometimes it's really necessary to do this so it's useful to have very thin things and you complicate very much because it's an issue and you have to use it sometimes especially for 3D you have to do this if you want columns it's good to do this UV so you create them so for this purpose it's perfect quite better because sometimes you need solid structures you need mechanical strength so it's useful as to do this with femtosecond laser but you can use very well this UV laser beam with a pinhole or a mask and you create very nice shapes so here is presented the lateral size of the voxels and the vertical size of the voxels so for many times when you you are doing such structures you have you can imagine it's not exactly like this but it's like a Gaussian beam in the same way and you can have a height of the peak and you take the width at half the width at half maximum so you consider there the waist of your structure and you can plot this waist function of the power you use to create them and also the function of exposure time and you can see if your process is still at two photon absorptions or at a moment increasing too much exposure time and the laser power you are slowly in the one photon absorption regime so it's a practical way to do this plotting here is the lateral size function on the exposure time and something else when we speak about exposure time we have implicitly the speed the scanning speed because finally is a time involved there and is a distance which is scan so if we have a lower scanning speed we increase the exposure time if we write with a very high speed we don't have time enough to interact the system with the laser and depends perhaps resolution is poor or we have very very very thin structures fabrication time is important in the economy of the process if it is an industrial one for example and we can see that it is function of the elementary time meaning the time required to create a voxel and you can vary from 1 to 10 milliseconds and this is function also on the scanning speed which is in their experiments is intense of microns you can see here a dragon here is a picture the desire picture and here the details are very nice seen but here the resolution is poor you cannot overlap the polymer structure with the initial image it was necessary just 19 minutes but if we take a look at this picture we can see clearly the details, address and so on 12 hours but this mean a combination between 1, 2 and 3D patterning strategies and we have to decide when we are doing some patterning which is the resolution we need do we need to invest so much time for some things or we can fix the problem in a more roughly way so this strategy is a roughly one and you can see so what we are doing when we need to create with high resolution a lot of structures we have to use some micro lens array or holographic multiple spot because we have no choice and now with your permission I will start to speak a little bit about metallic fabrication to photon absorption so we have the situation of absorbing of two photons with the same energy and we have a photochemistry induced at the focal point where we have a non-linear absorption which is proportional with the square of intensity we place a sample on the stage of a microscope here is the active layer and the glass substrate and we send we focus the laser beam in the active layer and in this way starting from metallications through the photo reduction we obtain neutral metal deposition at the focal point here and now I will invite to move I will succeed we have here is about T-tensifier laser femtosecond laser with 80 kHz repetition rate and 200 femtosecond part duration and we can see here this is a fabrication of a metallic wire and here is the final structure after we finish the process so in this way we have a photo reduction process which involves some components the first is the metallic salt in this case was gold salt we have a photosensitizer, we can use citrate, sodium citrate and we use the polyvinylpyroridone which is a very reactive polymer and then having these components ingredients through the reduction reaction from the cation of the gold salt which are very soluble in water we obtain at the focal point neutral metal which is insoluble in water for validation of the process we did some UV measurements, we used solution of the salt and we can see that when we irradiated the gold solution step by step the peak responsible for gold cation decrease and here in the visible part appear step by step increasingly some peaks which are responsible for the creation of the gold, gold colloids and we have the plasma resonance peak and if we did this in thin films we observe that the peak is thinner and less larger and this is due to the slower diffusion of the active species to the focal point and for reduction so concentration is lower and we started with that gold solution irradiating with a femtosecond laser and we obtain the colloids so it's not what we want in this situation we add some polymer we increase the viscosity about I spoke when I presented the thin film obtaining and in this way they are nice layers, nice lines we have to use a hydro soluble polymer as time as we dissolve the salt in water to have a homogeneous solution and here is an optical image in transmission for these lines the result after we remove the polymer matrix is the appearance of these metallic wires is an SEM image, is real and you can see here that they are detached from the surface and they are rolled up they are disconnected from the substrate we use untreated glass substrate and in this situation going closer we can see that that lines are continuous and they are real so I was very happy at that time so taking more pictures about the shape of these lines you can see that they are uniform as size and they are nice result so they are disconnected from the substrate but they have regular width that means we can keep under control the process as a chemical reaction chemical reactivity and in order to keep our structures on the surface and to use them for some other purposes I covered the glass substrate with a polymer layer additional which allowed then to put the active layer to create the structures which are nice result here you can see and then after the removal of the polymer matrix we have here in SEM a clean surface of polymer with nice lines which are attached on the surface and this is due to the covalent bonds which are forming between polymer and gold so in this way we are not doing self-assembly but in fact gold nanoparticles with some tiles which are coated on some substrate but we have also some sulfur or nitrogen atoms which are capable to fix in a very strong way structures on the surface the influence of the power because we discussed about this exposure time the power of the laser we can see here that in a series of lines written with increasingly powers we can see the shape is nice but the size the lateral size is enlarged and also we can see here that step by step somewhere at the down part of the structures we have somehow a little bit distorted part and in this way we can see that keeping under control the power is very good because otherwise we can affect the shape of our structures. Here it is seen the line after removing the matrix and we can see that it's not a road it's something with empty inside somebody removed the material from the inside and this was seen for all the structure we have done but the deep inside of the structures is bigger for higher powers than for lower powers and here we can see how the distance is varying with the laser power also we plotted the width of the lines versus laser power and it was about what I said before we can see for low laser power we have two photon absorption behavior and we have step by step the behavior of one photon absorption because we already have some colloids some metallic structures formed and this enhances the process and we cannot keep under control the process and we affect the shape of the lines. For the smoothness of the wires we can see that if we have higher powers we have nice nice nice smooth lines but they are big enough anyway it's not good in this way because they are thin that they are not nice resource so something has to be changed in the system and you can see here a cross section through these things there are two lines in AFM measurements here we can see double line because it's a shape we can see clearly here there are two walls we have here the distance between lines and I was speaking about the Gaussian type shape of the structures you can see here of course it's a 3D image here is the cross section and we can see here the width and here we can measure the distance between lines and the explanation for this type of shape is the existence of the thermal effect which is induced by the interaction of the laser beam with colloids or some metallic parts already created is a very simple experiment but this show us the influence of the power inside of the process so we have 10mW 20mW and I created horizontal and vertical lines and I force them to cross themselves to be sure there is no interference at this laser power and it's ok nothing is changed but here when I increase the laser power I observe that if I write the first line horizontal and then I start from the end to write the vertical one to be huge and just to be sure that is due to the interaction with the edge of the horizontal line I took this to cross the horizontal line and I discover that it's not a problem of vertical line the direction of the line in fact is a problem of meeting interference of laser beam with an already created structure and this proved clearly the thermal effect later in the lab in Cluj some of these things I've done during my PhD thesis in Grenoble in France but we did some transient absorption measurements on goal solution and we discover that there is an electron phonon coupling for some 10 nanoseconds picoseconds sorry and then we have a phonon phonon coupling which is around 600 towards 1000 picoseconds meaning that if we have a pulse duration of 200 femtoseconds and this relaxation time is in order of picoseconds we collect the effect of each pulse and finally we can have this huge effect so in this way we can realize that the structure are sensitive to the laser power and we have to change something inside of the system and I succeeded to obtain single wires and I use a droplet a droplet and I let it to evaporate but then I create the structures and I overcome the thermal effect the heating water has a high calorimetric thermal capacity and this calorimetric power so it is possible to absorb a large amount of water and to let the structures to work properly instead absorbing this amount of energy and in this way we have single wires which are nice resolved I succeeded in this situation to create also 3D because it was also in the droplet and it was nice resolved and also it is a silver 3D structure it is very very nice resolved I am very proud of this because I worked almost 2 months and a half to fix the structure on the surface because after you created it floats and you can you have to follow it until it stops it is heavy because it is huge it is almost 20 microns high but it was in silver and I was talking at the beginning that it is good to use also silver not only gold because if you have silver you can cover it with gold and you have the good properties having also the oxidation proof of the gold as we did at that time an electrolyte splitting of the structure you can see here is the fillers are more thinner and here is covered step by step with gold and here I almost covered with gold and here are some objects all experiment when you are using dry objective when you through the specimen because this is a 3D image and you have a Z-direction image and when you go through the specimen the aberration is increased and the resolution for example at 20 micrometers is not the same at the first of you have to take into account that not all the cover plates are 170 microns you have the working distance in this range but you can have 130 so you have place room enough to create 20 microns thickness of the layer and to do yourself so I use oil if I am working now with dry objective the resolution is not the same because we have worst numerical aperture is 1.3 versus 0.8 so it is the same magnification it is not the same resolution so it is easy for you but if you don't want to create a tower it is ok for a few tens of microns less than 40 it is ok so you can do this because the dry objective has more working distance there are some very very thin ok here is just examples for applications very interesting this was a dragon created by my colleague from Taiwan he was PhD student and he did this program for design this is computer age design and that is why he tried to realize to do it practically and somehow he failed because it is really difficult to create such interesting creature here is a microcapsule which is used for endoscopy to have a camera and you put inside and using optical tweezers you can push it and direct it in what place you want and you can take good information from inside without affecting the body here are some circuit elements in 2D and here is a scaffold for biological purposes and also here is a trying to decrease the size of the structures and of course femtosecond laser is an expensive tool so the people are trying to use sub-nano lasers in the neodymium is a green laser is cheap and you have in this way to compensate the repetition rate with the part duration so if you have a longer part duration you have to use a shorter repetition rate in order to have enough power to create your structures all these are done in 10 to 50 micro watts laser power and of course the size is very small exposure time is very short and you see here 50 microns and they did some calibration and they plotted here power versus the resolution of the line and here are for lithography with masks there are some microfluidic circuits it's really nice it's a good resin and here is about you ask one photon absorption we can use the same setup we have here the substrate but in this way we impress the entire path where the light is going so here we can see here the green laser spot and here is the dimension of the trace created with this one and we have a mask so we irradiate the entire volume and I use UV light for this and now you can see the creation of an inter-digitated electrode it's not working very good the system in this way we can see that we create this type of structure some inter-digitated electrodes the next step is to have the contacts and if we have this we can use it for electrochemistry for cyclic voltammetry because they are nano structure and they increase signal very much and I played a little bit with scanning speed and I played also with the size of the mask and I obtained in this series is the same shape but it is possible to see that the structure are thinner and thinner and here are the velocities I use and here they are some nice images I scan the whole picture and I connected with Picasso I put the pictures to create high resolution and huge image SCM measurements for that surfaces shows the presence of round uniform nanoparticles around 5 nanometers which are on the surface and they are fixed covalently fixed with some molecules and then here was just to see the benefits of doing lithography using a microscope to place a positioning system on it and so on because in this way I can create the structure I can see the structure I have the camera I can place a spectrophotometer I can record the spectrum to see exactly if I change the substrate and what I have inside where is the system and here is something very interesting we did in the lab in the framework of one of the lithography project I was working and these are two nanometer structures created in fluorescence photosensitive glass ceramics which has rare earth metals and that means we have inside serium one which is able to oxidize and oxidizing it gives one electron to silver cation which are reduced and they can create on the silicon nitrate or on the silicon surface these structures this is an AFM measurement and here if you can measure you can see is about two nanometers but at this size is a real question it is real or no it's artifact how can we prove this here we did a marker we are sure that we recognize the lines we are doing one big marker and another ten small lines and then we identify them here is the marker and here you see one, two, three lines but how to prove because what is AFM is a kind of measurement but you use a fit and finally is a function and in this way on a silicon nitrate we did a sputtering process deposition with gold for one second then this support is was investigated in TM and the distribution of nanoparticles was as it is seen here in the picture and it was about 1.5 and 2 nanometers size of the nanoparticle so the structure created and developed were also subjected to this sputtering for one second in the same condition and then we can see here that the channel there are many many smaller particles of gold and here is the channel and inside of the channel there are some particles and taking into account that we have from sputtering just 2 nanometers and less size if we have inside of the channel particles then means we did a calibration with real particles and we have 2 nanometers which is useful for data storage because we were in a project for data storage and advantages briefly for this type of things for polymer you cannot stop it when you want for the metallic things you can turn off the laser of course you have a small time still working but you can stop it or just replace the sample from the scanning speed the scanning plate and you can stop the process which this is an advantage another advantage is that if you use a microscope objective dry objective you have a working distance very long working distance and you can create some structures inside of capillars because you can penetrate it you put inside the salts your components and you create inside where normally you cannot do this so it's a very good advantage to work with metals and in conclusions before there is questions do I have time yes questions that we have time for questions alright so the conclusions are clear this direct writing laser technique is really useful it is creative it is flexible it is reliable and if you keep under control a lot of parameters meaning the chemical system and a very good optimization of the setup optical setup you can obtain good resolutions I will like to make the acknowledgement to the team I am working first of all is the project director from Bucharest I work with him very very much and very good activities I want to thanks to my colleagues Balertosa Aleksandra Falamaz which is here with me and we are working very good together Christian Tudoran for SCM measurements in our institute and also a great acknowledgement for the team who hosted me in France during my period it is about Patrice Moldek and the colleagues I have Olivier Stéphane and Givi Tramp from Minatec who helped me to do a lot of things I found measurements and I did everything discussing with him advising me it was really very good and these guys for SCM measurements especially Jean-François Moldek which taught me how to do very nice SCM measurements and to do real measurements without artifacts so support from national authority for financial support from these projects are grateful acknowledge and last but not least I would like to yes it's an honour for me I want to thanks to ICTP first of all because they voted this topic yes which was I moved yes it was a huge challenge for us then because I received this honour and huge responsibility to participate and to work inside I want to thanks to Professor Maria Calvo because he trusted me to Humberto to Victor and for Professor Nimela and from Professor Danilo for everything and to Frederica for her huge work and disponibility for everything and the financial support from ICTP is grateful acknowledge thank you very much