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Title:SLOW PHOTOELECTRON VELOCITY-MAP IMAGING (SEVI) SPECTROSCOPY OF CRYO-COOLED ANIONS
Author(s):Weichman, Marissa L.
Contributor(s):Neumark, Daniel; DeVine, Jessalyn A.; Kim, Jongjin B.
Subject(s):Comparing theory and experiment
Abstract:Slow photoelectron velocity-map imaging spectroscopy of cryogenically-cooled anions (cryo-SEVI) is a powerful technique for elucidating the vibrational and electronic structure of exotic neutral species. SEVI is a high-resolution variant of anion photoelectron imaging that yields spectra with energy resolution as high as 1 \wn. The preparation of cold anions eliminates hot bands and narrows rotational envelopes, enabling the acquisition of well-resolved photoelectron spectra for complex and spectroscopically challenging species.$^{1,2}$ Recently, cryo-SEVI has been applied as a spectroscopic probe of transition state dynamics on neutral reactive surfaces, through photodetachment of a bound anion similar in geometry to the desired transition state. In the benchmark F + H$_{2}$ reaction, we probe the transition state region through detachment of FH$_{2}^{-}$ and directly observe new reactive resonances. Comparison to new theory allows for the assignment of resonances associated with quasi-bound states of the transition state and products.$^{3}$ We also report spectra of the F + CH$_{3}$OH hydrogen abstraction reaction through photodetachment of the CH$_{3}$OHF$^{-}$ van der Waals cluster. We gain insight into the energetics and vibrational structure of transient complexes along the reaction coordinate of this complex polyatomic system.$^4$ Finally, we report a new cryo-SEVI study of vinylidene (H$_2$CC), a high energy isomer of acetylene, which is accessed directly through detachment of H$_2$CC$^-$. We find spectroscopic evidence that the isomerization of vinylidene to acetylene is highly state-specific, with excitation of the \nub{6} in-plane rocking mode resulting in appreciable tunneling-facilitated mixing with highly vibrationally excited states of acetylene.$^5$ \vskip1ex \hrule \vskip1ex \noindent $^1$Hock \textit{et al.} \textit{JCP} \textbf{137}, 244201 (2012); $^2$Weichman \textit{et al.} \textit{PNAS} \textbf{113}, 1698 (2016); $^3$Kim \textit{et al.} \textit{Science} \textbf{349}, 510 (2015); $^4$Weichman \textit{et al.} \textit{Nat. Chem.} \textbf{9}, 950 (2017); $^5$DeVine \textit{et al.} \textit{Science} \textbf{358}, 336 (2017)
Issue Date:06/22/18
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:APS
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/100796
DOI:10.15278/isms.2018.FC04
Other Identifier(s):FC04
Date Available in IDEALS:2018-08-17
2018-12-12


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