Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

J. Karhu, J. Nauta, M. Vainio, M. Mets�l�, S. Hoekstra, L. Halonen

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)

Abstract

A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν 1 + ν 2 + ν 3 + ν 4 1 + ν 5 - 1 in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm-1, the rotational parameter B was 1.162 222(37) cm-1, and the quartic centrifugal distortion parameter D was 3.998(62) � 10-6 cm-1, where the numbers in the parenthesis are one-standard errors in the least significant digits.

Original languageEnglish
Article number244201
JournalJournal of Chemical Physics
Volume144
Issue number24
DOIs
Publication statusPublished - 28 Jun 2016
MoE publication typeA1 Journal article-refereed

Fingerprint Dive into the research topics of 'Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy'. Together they form a unique fingerprint.

Cite this