Sub-doppler spectroscopy of the ν2 fundamental band and first hot band of the H3+ cation

Markus, Charles R.

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https://hdl.handle.net/2142/100794 Copy

Description

Title

Sub-doppler spectroscopy of the ν2 fundamental band and first hot band of the H3+ cation

Author(s)

Markus, Charles R.

Contributor(s)

• McCall, Benjamin J.
• Schrader, Alex W
• Esposito, Anne Marie
• Kocheril, Philip A.

Issue Date

2018-06-18

Keyword(s)

Mini-symposium: Frequency-Comb Spectroscopy

Abstract

The simplest polyatomic molecule, H + 3 , serves as an important benchmark for ab initio theory and is an important constituent of the interstellar medium (ISM). In the ISM, H + 3 initiates a chain of ion-neutral reactions which leads to more complex chemistry, and observations of H + 3 can be used to measure interstellar conditions such as the cosmic ray ionization rate.a For ab initio theorists, accurate calculations of the rovibrational structure of H + 3 require going beyond the Born-Oppenheimer approximation, and for its low-lying rovibrational states, agreement between theory and experiment has reached 0.001 cm−1 . b As these calculations begin to rival experimental measurements, new data are needed to benchmark future ab initio approaches. Using the technique Noise-Immune Cavity-Enhanced Optical Heterodyne Velocity Modulation Spectroscopy (NICEOHVMS)c to perform sub-Doppler spectroscopy and an optical frequency comb to accurately calibrate the frequency, we have expanded our survey of H + 3 to include transitions from higher rotational levels in the fundamental band and transitions in the 2ν 2 2 ← ν 1 2 hot band. Using combination differences, we have determined a number of energy level spacings in the ground state with an accuracy of ∼ 5 MHz, which are directly compared with state of the art ab initio calculations. We also discuss our progress towards calculating “forbidden” rotational transitions, including a possible astrophysical maser,d which requires our newly measured hot band transitions.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100794

DOI

10.15278/isms.2018.MG09

Copyright and License Information

Copyright 2018 Charles R. Markus

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