All talks start at 7.30pm in the Royal Society of Edinburgh, 22 - 26 George Street, with refreshments from 7.00 pm
Download the talk abstracts at: http://home.eps.hw.ac.uk/~phyrrt/IOP_Edinburgh_2018_19
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For more information contact Robert Thomson (R.R.Thomson@hw.ac.uk)
Tuesday 12th March 2019 - Dr Emma Springate (STFC Central Laser Facility, Rutherford Appleton Lab)
Lecture Title: Ultrafast science and lensless imaging with extreme ultraviolet pulses
Abstract: The Nobel-prize-winning technique of Chirped Pulse Amplification has enabled us to build high power laser systems producing ultrashort, femtosecond laser pulses at high repetition rates. These can be used as a strobe, to take freeze-frame snapshots of ultrafast processes, such as molecules breaking during chemical reactions, and then sequence them into high-speed movies.
In my lab, we use femtosecond lasers to produce coherent pulses in the extreme ultraviolet region (XUV) of the spectrum (100-10 nm wavelength, 10-100 eV photon energy) using a technique called high harmonic generation. This produces XUV pulses that are spatially and temporally coherent, emitted in a pencil beam, and tightly synchronized to the generating laser pulses. The high photon energy of XUV allows us to remove even tightly bound electrons from samples, using the photoelectric effect. By measuring the energies of the ejected electrons, we build up a map of changes in electronic structure of samples on ultrafast timescales. We have been able to apply this to observe what happens to electrons 2D materials such as graphene when they are illuminated, which could help us understand processes in photovoltaics, for example. The short wavelength of XUV can also be used exploited for high-resolution imaging. As it is difficult to make lenses for these wavelengths, we use a lensless imaging technique where we measure the scatter from the sample directly and then use algorithms in
place of a lens to reconstruct the image. We have been able to apply these to image mouse neurons at high resolution over a wide area, without staining or fluorescently tagging the sample.