 Now, I will move on to medium resolution sounds as I promised and small angle X-ray scattering together. So, let me remind you, I talked to about double crystal based medium resolution sounds in Dhruva. You can see a photograph of that on the guide tube. The monochromatic silicon 111, one which is inside the guide, you can see and the second monochromator is on the plate, so you can see that this is on the guide and we have a wavelength of 0.312 nanometer or it is 3.12 angstrom and you have the second monochromator which is shown here, here silicon disc which is rock and this one we rock it, I copy the rocking of the first silicon monochromator if there is no sample in between. When we put sample in between these two, then this sample, one is the, these are some inherent broadening the beam which is not the mosaic spread because it is a perfect single crystal is the Darwin width, it is the Darwin width, but when I put the sample between the two then that causes a broadening of the beam and when I rock the second crystal, when I rock the second crystal then I copy this broadening onto my detector and by this way I can go to a lower Q value because the inherent beam, the incident beam is very, very narrow and I can talk about length scales 42,000 nanometer. So, I have given a list of the lambda, delta lambda by lambda is very good one person and the flux is low, flux is low if must accept it because it is a single crystal diffraction which is coming from the first crystal from a polycrystalline for a polychromatic beam and I get only 500 neutrons per centimeter square per second and then thus detector is a BF3 detector, end on detector and the Q range please know that it is 0.003 to 0.17 nanometer inverse. So, if I transfer it into angstrom, 1 nanometer inverse is 0.1 angstrom inverse because 1 nanometer is equal to 10 angstrom that means this goes to 0.0003 angstrom inverse to 0.017 angstrom inverse. So, really speaking this is actually covering a different Q range compared to what I showed you earlier you see 0.01 to 0.2 angstrom inverse just I take an example of surfactant induced putty rampoli. So, I am in a different range of Q and different range of problems also. So, this instrument has been used for studying ceramics, cements, porcine cements, metallurgical alloys and micro granules. I will take an example from the micro granules. So, this being in a lower Q range it can see larger sizes. So, if I consider 1 by 0.003 it becomes 1000 divided by 3 that is a delta R resolution as per uncertainty principle and this you can see that you can see very large objects using this machine. So, I will just there will be many examples I will choose one example here these are silicon micro granules. Now, we have silicon nanoparticles, we have purchased silicon nanoparticles they are nanoparticles of small size. You put them in solution throw it in a spray dryer and let the water evaporate because spray dryer is heating and then what you get is structures like this. You can see the nanoparticles here and you can see the overall structure which is spherical. So, I am just here, but depending on the temperature at which you dry up the granules depending on the temperature now this assembly of these nanoparticles can be different structure. But first what I promised you how you can stitch together small angle neutron scattering and small angle excess scattering data. You can see here this part of the data the larger Q side was taken using exactly same structure we are doing small angle excess scattering and the principle of and the design of instruments are very very similar. You have a large flight path you have a collimator to collimate down the beam and you have a detector. So, this data and this data they are stitched together and you can see that we have covered a very large Q range 10 to the power minus 3 nanometer inverse that means 10 to the power minus 4 angstrom inverse to 1 angstrom inverse and basically in the overlap region we match the sample I mean we basically scale the excess data and also scale the error functions. So, and then we get a continuous curve. So, this is the matching of m sands here with sacks this is used at other places also where you can even do in situ I will use an example in my later part. So, this is a stitching of sands data and sacks data to cover a large Q range and you can see the fits this fits give me the basically the dimension and the structure of the assembly of nanoparticles. So, this is a commercial spray dryer which is available with us this is a very large name scale 0.5 micrometer means 5000 angstrom, but you can see depending on the drying temperature check this depending on the drying temperature you get various right from spherical you can get something like a toroidal toroidal toroidal structure you will get even interesting structures I will come to shortly. So, depending on the heating you can play the structure of this I can say my assembly of nanoparticles and that makes a very interesting thing that here while we were drying in the spray dryer we added an E. coli E. coli bacteria which you know which causes stomach upset E. coli bacteria in the solution. So, what happens when these structures form they also accommodate the E. coli in the structures E. coli in the structures and then you can see this is the structures form on drying and if I burn out the E. coli then we have these gaps we have these gaps which can accommodate E. coli in this and an attempt was made I have given the reference here an attempt was made now that we first when we were drying the silicon particles we added an E. coli bacteria to it so and then we burnt out the E. coli bacteria and you please see it is I Q multiplied by Q to the 4 and it is again stitched in sounds data and sacks data this rise because we have multiplied it by Q to the power 4 to see the porous region and the surface area of this structure. So, when we do it then there are gaps in it which can accommodate E. coli and then when we use try to use it as a water filter interestingly it could filter out the E. coli E. coli bacteria. So, this is a work which I would say we started with micelles went into protein unfolding of biology this is almost like a you can say application where if we use assembly of such nano structures then you can actually make a setup we know that water filters are used in every room here this water filter can actually remove E. coli bacteria from water this setup was made and this was interesting. So, with this example I come to an end of the Q range that can be used in Dhruva and the kind of studies that have been undertaken on these instruments and I you can see that the small angle neutron scattering is important for basic as well as applied field from the examples in micelles protein unfolding and this removal of E. coli bacteria. Now, this same science machine had also been used to understand the loading waste loading in cement matrix. Now, waste loading means it's an important thing in nuclear technology when we run reactors we create lots of waste lots of waste means nuclear waste which needs to be first immobilized and then stored immobilized they are immobilized in glasses they can also be immobilized in cements because cement has lots of pores and those pore sizes were studied using m-sounds and we could see that the fractal dimensions decrease when you start loading this cement with nuclear waste and how the fractal dimension changes there is also another example of application of sands to understand the importance of utilizing cement for immobilizing nuclear waste. With this I come to some other examples actually these are earlier examples this work these work these work on various polymers were undertaken at NIST in USA. So, one is that you can see that the polymers are basically linear chains chains and in solutions they fold up they tend to fold up and the radius of generation from the guinea region can be found out. So, this is a Pleronic's Pleronic's polymer and in deuterated water this gives an Rg of 34 angstrom that means this folds up with a structure which has got a radius of generation which is 34 angstrom and similarly dendrimer is another multi branch polymer also studied there and you can see that the log plot is a straight line various values of because the slopes are different the radius of generation differs based on the concentration of the dendrimer in deuterated water. So, this is another example of finding out radius of generation of polymers using small angle neutrons scattering this work was done at NIST in USA NIST reactor in Geethyspar. I will just quickly mention the sands instruments at various major sources I have taken example of a sands instrument of the sands instruments that are available at ISIS neutron source palatial neutron source in Rutherford Appleton laboratory there are number of small angle machines because of their high demand one the most used is low-cube sandal 2D, larmer and zoom all of these are small angle neutrons scattering machines and the structure of the machines are similar to what you find in a reactor only thing is that here we use time of flight techniques to determine the lambda and the cube values otherwise rest of the structures remain same. So, like low-cube is a relatively simple instrument so always the flight path depending on your collimation and the intensity of neutron that you can retain you try to make the flight path long because you need good collimation and you make the flight path long. So, there is a long flight path before the sample and after the sample you have a long flight path if it was the further you take your detector if I put a two-dimensional detector on the detector the small cube value a small cube scattered data will be well separated from the direct beam if you can go further apart. So, we have to have a large flight path before the sample to collimate the beam and we have to have a large flight path after the sample to determine small cube data to get the small cube data. So, there is a 11 meters evacuated beam line down with the neutrons fly toward the sample I have taken it from their source and then we have the heater fixed two-dimensional detector 4 meters high sometimes you can play with the distance of the detector depending how much resolution you want and low-cube can investigate sizes from 1 to 100 nanometers length scale up to 400 nanometer can be proved in highly anaesthetic system. Similarly, I have just given what they have written in their site for sounds to leave. So, basically size, shape and internal structure and spatial arrangement these are important size, shape like many times we have fitted products through ideal scene we have found out the fractal dimension so those are the internal structures and the spatial arrangement in nanomaterials soft matter and all the things I discussed so far they are soft matter soft matter means the viscoelastic they have they are like they have a very small shear stress to sort of shear their shapes and they can bend easily and that is the definition of soft stress as a soft material as I told you that the studies of them are very important today for science as well as for applications. So, this is just a schematic of the low-cube instrument you can see that the large flight path before the sample and there is a large flight path after the sample excuse me which this dictates the collimation this dictates the resolution with collimation on the detector. Similarly, if I talk about the high flux research reactor at ILL Grenoble there are D11, D22 and D16 there are more I just chose these they are the small angle neutron machines and you can see the polymers and collides I gave you examples on polymers, polymer blends, micelles, dendrimers I showed you the dendrimers used with rigid spacer based gemini surfactants phase separations in alloys and gas glasses I didn't show an example of that super alloys biological macromolecules I will also I will also give an example of flux line lattice in superconductors it is a very very interesting work extremely interesting from fundamental science and I will explain this to you and similar range of studies that you can deal with D22. So, now I will talk about flux lattice line again the structure is very similar you can see there is a neutron guide large flight path and I just show you this keep showing you the schematics because small angle machines have a general criteria of a large flight path before the sample to collimate the beam and the large flight path after the sample to dictate or to detect the good resolution for small angle machines and ok I must mention here these detectors are actually two dimensional position sensitive detector that means I cannot discuss with you the functioning of it I discussed with you earlier about one dimensional position sensitive detectors that the position is sensed on a wire wire it is where the neutron beam hits depending on the charge they get on both sides now in these things in these detectors two dimensional detectors you have got a cross of these wires in the very simplistic way of trying to tell you now if I can if the neutron hits here I can find out on the X axis and Y axis where the neutron has been detected and assign the intensity to that particular pixel and ultimately you get a structure figure like this so if it is a two dimensional detector you might get a circular cone of intensity on this which is small angle intensity so this is a small angle intensity because of this distance this X and if this L is large then X by L will be giving me the small angle intensity now it may introduce you to flux lattices I have jumped the subject so I have the responsibility of telling you what is a superconductor and what is a d-wave superconductor the thing is that we must have been taught in your master's degree that in superconductor you have cooper pairs and cooper pairs form between two electrons and also at a macroscopic length scale if I plot magnetic versus field in a type 1 superconductor up to some screen the system resist so it is minus M the entry of the field and then the superconductivity is destroyed and the field enters the medium but in type this is type 1 type 1 in a type 2 superconductor the at some field it starts penetrating penetrating the medium and then so then there is a field called hc1 hc1 where the field starts penetrating the medium and at the field hc2 the field completes the penetration and the superconductor becomes normal here in type 1 it suddenly goes normal and the superconductivity disappears so superconductivity is a medium which is perfect superconduct is known as perfect diamagnet which does not allow does not allow entry of magnet field but in type 1 it suddenly allows the magnetic field entry and becomes normal in type 2 superconductor there are vortices that means magnet is in magnetic flux lines are in form of vortices and these vortices actually if I take a superconductor cross section there are these vortices there are these vortices which can come this is because it was shown by because of Gorkov that the surface energy of these vortices here they are positive so they don't form but in type 2 the surface energy is negative so increasing surface energy helps to reduce free energy and you have vortices this kind of vortices so these are magnetic flux lines flux lattice is sort of embedded in the basic matrix so that means these will be superconducting parts and the vortices are because they are magnetic they are non-superconducting parts this is a mixture of these so now the question comes that if there are vortices if I allow them to form a lattice now each vortice is repelling each other so when two materials two particles are repelling each other equally then these vortices should form a hexagonal lattice so this is a hexagonal lattice so now the length scale of this hexagonal lattice is large unlike crystallographic structure there is an ordered structure here but the length scale is large of third of tenths of nanometer so that means even if I see a Bragg peak from this lattice it should be at the low key and that is where the science becomes very important science becomes very important now I will give you an example a very very interesting example what is shown so okay I am sorry I overshot a little before I talk about the vortices first let it I should have mentioned this I am sorry about this actually in case of D22 at ILL you have the facility of doing small angle neutron scattering and small angle extra scattering simultaneously on the sample so you can do suns in this direction and in the same sample you have got a small angle extra machine which detects the sax data in this direction so you cross the sample with neutron beam and small angle extra beam and you can institute studies and you can stitch the data so this is what actually I was talking about that in our system we have to take out the sample from M-sounds and collect the sax data here you can do it at the same time in D22 now I will go back to vortice lattice so vortice lattice in a DOF superconductor using suns that is my target so I talked about type 2 superconductor in which there are vortices now in conventional earlier superconductors the coupling between the electrons where between up spin and down spin and they were called SOS superconductors and the SOS superconductor had an order parameter which is spherical and for a spherical S-wave superconductor the vortice lattice as I told you it should be an hexagonal structure now comes a new high-tc superconductors like YBCO, itreumberium copper oxide it's a D-wave superconductor the D-wave superconductor means basically you can see this is a D-wave order parameter so unlike this it has got a D-wave like this and it's a copper oxide plane copper oxygen plane in which its holes are doped and basically it's a D-wave superconductor and without getting into the argument how D-wave superconductor is justified but there are some observations in the D-wave superconductor one is that under high field this hexagonal lattice which I find in SOS superconductors initially at low field for D-wave superconductors they will form a hexagonal lattice between the vortices that are embedded in the matrix but as we increase the field the hexagonal lattice should distort to a square lattice now let's see this is the experimental result this is done at a small angle instrument you can see this is the low field data this is the 4 tesla data and as you go to nearly 11 tesla you get the square lattice so this experiment is a huge justification for accepting that this YBCO is a D-wave superconductor actually these are the new justifications for accepting that the superconducting order parameter need not be just S-wave square lattice and this square lattice is an observation of high field vortex lattice this is a live picture from a YBCO sample this is an excellent result and you can see that so far we have been discussing applications chemistry this is deep physics observation where it justifies of the fact that YBCO is D-wave superconductor I will come back to this superconductor later when we talk about thin films but with this example I draw a curtain on examples in SANS experiments and now we will move forward to other metroscopic techniques like neutron reflectance