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 Title: Toward precision mid-infrared spectroscopy on the OH radical Author(s): Meek, Samuel Contributor(s): Furneaux, John; Fast, Arthur Subject(s): Fundamental physics Abstract: Measurements of vibrational transitions in small molecules can be used to test for a possible time variation of the electron-proton mass ratio.\footnote{J.-P.\ Uzan. {\it Rev.\ Mod.\ Phys.} {\bf 75}, 403–455 (2003).} In our experiments, our goal is to measure two-photon $v = 2 \leftarrow v = 0$ vibrational transitions in the hydroxyl (OH) radical near $2 \times 3500$ \wn{} with a relative accuracy of $10^{-14}$. Reaching this level of accuracy requires a mid-infrared laser with a linewidth of much less than 1 kHz, as well as the ability to compare the frequency of this laser with an absolute frequency standard. To achieve the high short-term stability necessary for such a narrow linewidth, we are implementing a 532-nm CW reference laser by locking a frequency-doubled Nd:YAG laser to a molecular iodine transition using saturated absorption spectroscopy. Similar setups have demonstrated relative stabilities of around $10^{-14}$ at the one-second timescale.\footnote{Döringshoff, K., Mohle, K., Nagel, M., Kovalchuk, E. V., Peters, A: High performance iodine frequency reference for tests of the LISA laser system. \it{EFTF-2010 24th European Frequency and Time Forum} (2010).} The stability of this reference laser will then be transfered onto the idler of a 1064-nm-pumped optical parametric oscillator (OPO) using an optical frequency comb as a transfer oscillator. The frequency comb will also be used to measure the absolute optical frequencies of the various lasers and compare them to a GPS-linked radio frequency reference, providing long-term stability and absolute accuracy for the spectroscopic measurements. Issue Date: 2016-06-24 Publisher: International Symposium on Molecular Spectroscopy Genre: Conference Paper/Presentation Type: Text Language: En URI: http://hdl.handle.net/2142/91199 Rights Information: Copyright 2016 by the authors Date Available in IDEALS: 2017-01-26
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