Linear probing of molecules at micrometric distances from a surface with sub-Doppler frequency resolution

Abstract

We report on precision spectroscopy of sub-wavelength confined molecular gases. This was obtained by rovibrational selective reflection of $\mathrm{N}{\mathrm{H}}_3$ and $\mathrm{S}{\mathrm{F}}_6$ gases using a quantum cascade laser at $\lambda \approx 10.6\mu m$. Our technique probes molecules at micrometric distances ($\approx \lambda /2\pi$) from the window of a macroscopic cell with sub-MHz resolution, allowing molecule-surface interaction spectroscopy. We exploit the linearity and high-resolution of our technique to gain novel spectroscopic information on the $\mathrm{S}{\mathrm{F}}_6$ greenhouse gas, useful for enriching molecular databases. The natural extension of our work to thin-cells will allow compact frequency references and improved measurements of the Casimir-Polder interaction with molecules.

arXiv commentaccepted for publication in Physical Review Letters

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Cited by in corpus (7)

• Atom-surface physics: A review
• Highly coherent phase-lock of an 8.1 $\mu$m quantum cascade laser to a turn-key mid-IR frequency comb
• Near-to mid-IR spectral purity transfer with a tunable frequency comb: methanol frequency metrology over a record frequency span
• Probing molecules in gas cells of subwavelength thickness with high frequency resolution
• Wavelength modulation laser spectroscopy of N${}_2$O at 17 $\mu$m
• Demonstration and frequency noise characterization of a 17 $\mu$m quantum cascade laser
• Selective reflection Casimir-Polder spectroscopy in vapor cells: the influence of the thermal velocity distribution