this post was submitted on 12 Jun 2023
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I'm a PhD candidate too - my contract is finished now, but I am still writing my thesis. So I am currently at the awkward intersection of finishing a thesis and looking for a job.
My PhD focus is in applying time-resolved spectroscopic techniques to study the excited state dynamics of molecules. Basically, these are experiments in which a pulsed laser is used to excite the sample and a second probe light is used to measure a change in the absorption in response to the light. By measuring these changes in the absorption as a function of time, and applying quantum chemical methods to calculate the spectra of potential intermediates, one can sort of recreate a molecular movie of what the molecule is doing after it absorbs light with a time resolution of femto to picoseconds. The materials that I study are organic dyes that are useful for microscopy, as well as molecules that respond to EUV light for applications in photonanolithography (for making the very small transistors in computer chips).
I am also an "amateur" scientist when it comes to biology, as many of my hobbies are nature-based and it's not like I can turn off the science bug when it comes to hobbies.
Well that's fascinating! The technique sounds a little bit like a cross between Raman and EXAFS/XANES? (Probably just because those are two techniques I happen to be familiar with though.)
Raman and EXAFS/XANES are techniques to probe different types of molecular transitions. Vibrational raman probes molecular vibrations, and XANES probes electronic transitions due to excitation of core electrons. Each technique will help you obtain different molecular properties. The standard approach is to apply these methods to do "static" absorption studies, meaning that one studies the transitions induced by these light sources in order to obtain molecular information of a given sample. The time-resolved techniques expand these measurements along the time dimension, so you can measure these properties but in a sample that is changing extremely quickly in response to a trigger (usually light).
So, it is not that the technique is a cross between these, but rather an approach to take Raman, or XANES, or IR-spectroscopy, or UV/Vis absorption spectroscopy, and then apply it in a time-resolved manner. You can usually take any spectroscopy technique and add "time-resolved" at the beginning and you will find someone doing that. Of course, some techniques are easier to perform in practice than others. I have done some time-resolved XANES experiments, and for those we need to go a synchrotron and the experiment is really tricky. A time-resolved UV/Vis can be done in many university labs. I don't have practical experience with Raman experiments.
That's a really clear explanation, thank you!