Stepping across the dissociation threshold of the I−·(H2O) complex: Resonance enhanced two-color IR-IR photodissociation (R2PD)

Yang, Nan

Permalink

https://hdl.handle.net/2142/100840 Copy

Description

Title

Stepping across the dissociation threshold of the I−·(H2O) complex: Resonance enhanced two-color IR-IR photodissociation (R2PD)

Author(s)

Yang, Nan

Contributor(s)

• Johnson, Mark
• Steele, Ryan P
• Talbot, Justin J
• Kelleher, Patrick J.
• Duong, Chinh H.

Issue Date

2018-06-19

Keyword(s)

Mini-symposium: New Ways of Understanding Molecular Spectra

Abstract

The X−·(H2O) (X=I, Cl, F) clusters ion provide a microscopic window into the intracluster energy relaxation dynamics that ultimately lead to dissociation when excited above threshold (Do). Here we explore the spectra of simple binary complexes of one water molecule with an iodide ion when the system is excited to vibrational levels that span the energy range through Do. This is accomplished by recording the vibrational photodissociation spectra of different vibrational excited states of X−·(H2O) using a two-color, IR-IR photodissociation technique. We first quantify the ground state spectra by recording the single photon absorption spectra of cryogenically cooled cluster ions with messenger tag technique. Then we fix the pump laser frequency on a transition known to the ground state cluster ion and scan the probe laser to obtain the excited state photodissociation spectra. Owing to the long lifetime of the vibration excitations in this class of clusters, each pump laser excitation frequency yields a different spectrum (the traces on the right in the figure). This provides an opportunity to obtain a kind of 2DIR spectroscopy (left bottom figure) of cryogenically cooled gas phase ions. The result is a cluster variation of the vibrationally-mediated photodissociation experiments pioneered in the 1990s by Crim and Rizzo on polyatomic molecules. In the cluster regime, we find remarkably long lived (greater than 50 µs!) vibrational levels 300 cm−1 above the dissociation threshold and surprisingly localized excitations for the bound OH stretches. This feature allows us to follow many pathways up the vibrational landscape far beyond the dissociation limit.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100840

DOI

10.15278/isms.2018.TH04

Copyright and License Information

Copyright 2018 Nan Yang

Owning Collections