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Atomic Physics Seminars

ics Atomic
Monday, January 21, 2019
3:30 PM
Physics Building, Room 204
Note special time.
Ali Azarm [Host: Bob Jones]
University of Arizona
"Ultrafast intense laser interaction with molecules and nanostructures"

Strong laser field interaction with materials is rich in physics and chemistry, and gives rise to variety of spectacular phenomena ranging from multiphoton/tunneling ionization to high harmonics generation. In this talk, I will present three of these intriguing phenomena that I have investigated.

First, I will explain neutral dissociation of hydrogen molecule in strong laser field through multiphoton super-excitation. I will demonstrate the experimental results of fragmentation of hydrogen molecules in a strong laser field including observation of Balmer lines from hydrogen atoms and measuring the upper limit of the lifetime of the super-excited states by an ultrafast pump and probe experiment [1].

The second part of the talk is dedicated to optical gain and population inversion in ions at 428 nm wavelength through high-resolution spectroscopy. I will clarify how sufficient dissimilarity of rotational distributions in the upper and lower emission levels could lead to gain without net electronic or vibronic population inversion [2].

Finally, at the third part of the talk, I will show the results of use of femtosecond laser pulses to melt indium semi-spherical nanostructure (r~175 nm) and shape them by high spatial frequency laser induced periodic surface structures into linear microstructures of 2 μm long in the direction of laser polarization. The understanding of the modification process, melting and moving in the nano-grating structured field, pave the way to design nanostructures of arbitrary shapes at the sub-wavelength scale [3].

[1] A. Azarm, D. Song, K. Liu et al. J. Phys. B: At. Mol. Opt. Phys. 44 (2011) 085601

[2] A. Azarm, P. Corkum, P. Polynkin, Phys. Rev. A Rapid Comm. 96 (2017) 051401(R)

[3] A. Azarm, F. Akhoundi, R. A. Norwood et al. Appl. Phys. Lett. 113 (2018) 033103

To add a speaker, send an email to phys-speakers@Virginia.EDU. Please include the seminar type (e.g. Atomic Physics Seminars), date, name of the speaker, title of talk, and an abstract (if available).