Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

The 3-0 Quadrupole Band in H2 by Cavity Ring-Down Spectroscopy



D C. Robie, Joseph T. Hodges


Several lines in the S and Q branches (including the previously unobserved Q32 and Q33 lines) of the 3-0 quadrupole band of H2 have been detected by cavity ring-down spectroscopy using a multimode laser with a long cavity. The noise equivalent absorption coefficient was as low as 4 10-10 /cm Hz, permitting signal-to-noise ratios up to 1000. Peak areas were measured at densities between 0.1 and 2.8 amagats at 296 K. Observed linestrengths in the S branch are consistent with earlier measurements, and about 10% below theoretical calculations. Observed linestrengths in the Q branch are about 30% below theory. Evidence is presented that collision-induced absorption is significant in these conditions.PACS numbers: 33.20.Kf, 33.70.Fd, 96.35.Hv
Journal of Chemical Physics


cavity ring-down, hydrogen, line strength, quadrupole moment


Robie, D. and Hodges, J. (2021), The 3-0 Quadrupole Band in H2 by Cavity Ring-Down Spectroscopy, Journal of Chemical Physics (Accessed May 29, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created October 12, 2021