News & Events

Leah G. Dodson, Ph.D.

Posted on April 3, 2020


Date - April 3, 2020
1:00 pm - 2:00 pm


Assistant Professor
Department of Chemistry and Biochemistry
University of Maryland College Park
Talk Title: Cryogenic Spectroscopy of Molecular Ions: Applications and Future Directions


Preparation of cold (< 50 K) molecules and ions in the gas phase enables discoveries of the fundamental chemical and physical properties of these species. In this talk, I will show how we investigated the intrinsic photophysics of nitrophenolate isomers (meta, para, and ortho) at low temperature using photodissociation mass spectrometry in a cryogenic ion trap instrument. This study revealed that each isomer has distinct photophysics that affect the excited state lifetimes, as observed experimentally in their spectroscopic linewidths. Visible-light-induced excitation of m-nitrophenolate gives rise to well-resolved vibronic features in the spectrum of the S1 state that have been assigned using a Franck-Condon analysis. The para and ortho isomers have broad spectra – even at cryogenic temperatures – due to their shorter exited state lifetimes and spectral congestion. I will present computational evidence for mixing of the first and second excited states of o-nitrophenolate, leading to significant additional broadening in the experimental spectrum.

I will also introduce the astrochemical goals of my new research group at the University of Maryland and describe how we will use similar low-temperature techniques to prepare and study molecules and ions at temperatures relevant to circumstellar and planetary environments.