High signal-to-noise ratio laser technique for accurate measurements of spectral line parameters
A. Cygan, D Lisak, S. Wojtewicz, J. Domyslawska, Joseph T. Hodges, R.S. Trawinski, R. Ciurylo
We present a new cavity-enhanced technique for the precise measurement of absorption line shape and line position. This approach, which combines high-bandwidth locking of a continuous wave probe laser with frequency-stabilized cavity ring-down spectroscopy, enables long-term signal averaging and yields high-resolution spectra with a relatively wide dynamic range and low detection limit. By probing rovibronic transitions of the oxygen B-band near a wavelength of 689 nm, we demonstrate exceptionally precise measurements of absorption line shape and line position. We report a signal-to-noise ratio of 220,000:1 a minimum detectable absorption coefficient of 2.4E-11/cm and line center measurement with a precision of 26 kHz. In our measurements of self-broadened oxygen spectra, careful line shape analysis revealed a subtle line shape asymmetry caused by the speed dependence of the collisional shift. The precision achieved enabled us to quantify systematic line shape deviations that were approximately 1 part in 80,000 of the peak absorption. We also discuss how this method can enable experiments that address a number of fundamental physical problems including the accurate measurement of the Boltzmann constant and tests of the symmetrization postulate.
, Lisak, D.
, Wojtewicz, S.
, Domyslawska, J.
, Hodges, J.
, Trawinski, R.
and Ciurylo, R.
High signal-to-noise ratio laser technique for accurate measurements of spectral line parameters, Physical Review Letters, [online], https://doi.org/10.1103/PhysRevA.85.022508, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=909706
(Accessed November 29, 2023)