High-resolution linear spectroscopy on a micrometric layer of molecular vapor

Darquie, Benoit

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https://hdl.handle.net/2142/100629 Copy

Description

Title

High-resolution linear spectroscopy on a micrometric layer of molecular vapor

Author(s)

Darquie, Benoit

Contributor(s)

• Laliotis, Athanasios
• Bloch, Daniel
• Rios Leite, Jose Roberto
• Shelkovnikov, Alexander
• Tokunaga, Sean
• Maurin, Isabelle
• Lukusa Mudiayi, Junior

Issue Date

2018-06-19

Keyword(s)

Instrument/Technique Demonstration

Abstract

Molecular rovibrational transitions can potentially provide high-resolution frequency references for the visible to the mid infrared including the telecommunications window at 1.5µm (C2H2 or HCN). Going towards compact miniaturized molecular spectroscopy is an extreme challenge as molecular transition probabilities are weak and long propagation length is required. Compact systems based on hollow core fibers filled with acetylene gas (C2H2) at high pressures have been presenteda but the propagation length remains macroscopic. Additionally, collisional broadening (high pressures) or the Doppler effect hinder the available resolution. Here we present selective reflection (SR) spectroscopy measurements on a molecular gas of NH3 and SF6 molecules at 10.6µm. Frequency modulated SR is a high-resolution (sub-Doppler) technique, linear in laser power that is essentially only sensitive to a layer of molecules whose depth is defined by the wavelength of optical excitation (∼ λ/2π), even when the cell remains macroscopic. Initial measurements, were performed with a CO2 laser, subsequently changed for a more user friendly QCL laser rendered compatible with high-resolution spectroscopy. The core of our experiments is performed on the P(1) line of ammonia at 948.23cm−1 with best resolution limited by the laser linewidth (∼ 0.5MHz). For pressures below 50mTorr (collisional broadening ∼ 1.4MHz) the hyperfine structure of ammonia can be clearly resolved. Our experiments pave the way towards miniaturized molecular frequency references such as nanocellsb,c , and allow us to envisage the first precision measurements of the Casimir-Polder molecule-surface interaction.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100629

DOI

10.15278/isms.2018.TI07

Copyright and License Information

Copyright 2018 Benoit Darquie

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