Infrared Comb Spectroscopy of Buffer-Gas-Cooled Molecules: Toward Absolute Frequency Metrology of Cold Acetylene

Abstract

We review the recent developments in precision ro-vibrational spectroscopy of buffer-gas-cooled neutral molecules, obtained using infrared frequency combs either as direct probe sources or as ultra-accurate optical rulers. In particular, we show how coherent broadband spectroscopy of complex molecules especially benefits from drastic simplification of the spectra brought about by cooling of internal temperatures. Moreover, cooling the translational motion allows longer light-molecule interaction times and hence reduced transit-time broadening effects, crucial for high-precision spectroscopy on simple molecules. In this respect, we report on the progress of absolute frequency metrology experiments with buffer-gas-cooled molecules, focusing on the advanced technologies that led to record measurements with acetylene. Finally, we briefly discuss the prospects for further improving the ultimate accuracy of the spectroscopic frequency measurement.

Nuclear Spin Relaxation in Cold Atom–Molecule Collisions

“…We apply our methodology to study transitions between the different nuclear spin sublevels of 13 C 16 O in cold collisions with 4 He buffer atoms. This system is experimentally relevant as buffer-gas-cooled diatomic and polyatomic molecules have been probed spectroscopically in a number of recent experiments. − We perform rigorous coupled-channel quantum scattering calculations based on an accurate ab initio potential energy surface of He-CO, focusing on transitions between the nuclear spin sublevels of the ground ( N = 0) and the first excited ( N = 1) rotational states.…”

“…Nuclear spin-flipping collisions are responsible for the stability of the nuclear spin states of molecules immersed in a cold inert buffer gas (such as He or Ne). These systems can be realized experimentally using cryogenic buffer gas cooling, ,− and they are interesting for a variety of reasons. First, preparing molecules in a single nuclear spin (or hyperfine) state enhances the sensitivity of spectroscopic measurements − and is essential for the initialization steps of molecule-based quantum information processing protocols.…”

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

“…The last one seems to be the most detailed, and it is precisely this that we will try to implement in the course of our narrative. As it should be expected, a priori, most of the publications in this direction are devoted to organic compounds, and primarily organic molecules; these include, with varying degrees of correctness, publications [ 1 , 2 , 3 , 102 , 103 , 104 , 106 , 108 , 112 , 117 , 118 , 119 , 121 , 124 , 127 , 128 , 130 , 131 , 132 , 133 , 135 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 146 , 147 , 148 , 151 , 153 , 154 , 156 , 157 , 164 , 165 , 166 , 168 , 171 , 172 , 174 , 176 , 178 , 180 , 183 , 185 , 186 ]. Much less space is occupied by the works related to polymeric (in fact, to a high molecular weight) compounds [ 113 , …”

“…In review [ 161 ], devoted to the so-called macrolide antibiotics, a description of advanced physicochemical methods for elucidating the structure and interaction of macrolide antibiotics in solid state and solution is presented, and their main advantages and disadvantages are considered. Finally, review [ 176 ] systematizes and characterizes the latest advances in precision rotational-vibrational spectroscopy of neutral (mainly organic) molecules, within which spectra are obtained by using infrared frequency combs, either as direct probe sources or as ultra-accurate optical rulers.…”

High-resolution spectroscopy of buffer-gas-cooled phthalocyanine

“…Although buffer-gas cooling is a conventional method 3 , 4 , it has recently attracted considerable attention 5 , 6 . This is because various applications using the quantum control of cryogenic molecules have recently been proposed in fundamental physics, quantum information, and ultracold chemistry 7 .…”