 Hello, welcome to the NPTEL course on laser spectroscopy. My name is Anindya Dutta. I am a professor of chemistry in IIT Bombay. This course which is mainly meant for PhD students who are interested in ultrafast spectroscopy is in our institute often credited by our MSC chemistry students in their final year and sometimes by a bachelor of science chemistry students as well. So, the idea here is to understand how lasers work and how they can be used especially ultrafast lasers to understand interesting phenomena in chemistry. You can say that this is following laser physics from the perspective of a chemist. So, what we will do here is that first of all we are going to introduce why we need to study ultrafast processes in the first place. Then we will spend a considerable time in understanding how ultrafast pulses are generated, measured and what one can do with them. We will study several experimental techniques like time correlated single photon counting, transient absorption and femtosecond optical counting. We will also discuss rudiments of non-linear optics because you cannot really do laser spectroscopy without using non-linear optical elements in some form or the other. Finally, when we are done with discussion of the equipment in not in much detail. As I said from a chemist perspective, we are going to discuss some phenomenal experiments that have defined this field. So, the idea of this course is to generate interest among students who might later on want to take up careers pursuing problems that are followed by laser spectroscopy in general and ultrafast processes, ultrafast dynamics in particular. I hope that this course will be a good learning experience for all students. Thank you.