Note: Computation of collision-induced absorption by dense deuterium–helium gas mixtures

Testing the ab initio quantum‐scattering calculations for the D2–He benchmark system with stimulated Raman spectroscopy

“…Because H 2 and D 2 have no first‐order infrared spectrum, DPR light scattering is a useful tool to study such systems and test computational methods. Another approach is the study of collision‐induced transitions: Collision‐induced absorptions in H 2 and its isotopologues (D 2 and T 2 ) have been recently computed and compared with experiments in order to test the induced dipole surface and a potential energy surface for the H 2 –He system. Other alternative techniques are electric quadrupole spectroscopy and Raman spectroscopy of either rovibrational or purely rotational transitions.…”

Recent advances in collisional effects on spectra of molecular gases and their practical consequences

“…Their method is usually quantum mechanical, but ignores anisotropic components of the intermolecular potential ("isotropic approximation"). Investigations were made for pure H 2 [401][402][403] and for H 2 with He [404], with corresponding studies for deuterium and tritium in [405][406][407]. Most of those studies include comparisons with laboratory measurements at several different temperatures, and they are done using recent ab initio potential and dipole data.…”

Comparison of the Calculated Collision-Induced Absorption Spectra by Dense Hydrogen-Helium, Deuterium-Helium, and Tritium-Helium Gas Mixtures

“…These surfaces have been obtained using quantum chemical methods [7,8]. The thus computed collisioninduced absorption spectra have been compared to laboratory measurements at infrared and microwave frequencies [7][8][9]. Close agreement between theory and experiment has been observed [1].…”

“…While the electronic structure of X 2 -He is virtually the same for all hydrogen isotopes X = H, D, or T, the collisional dynamics and molecular scattering wave functions are different for the different species [9,10]. Whereas numerous laboratory measurements of collision-induced absorption spectra of H 2 -H 2 and H 2 -He exist, far fewer laboratory measurements of the CIA of D 2 -He exist, and no laboratory measurements of the CIA of gaseous mixtures of T 2 -He are available thus far.…”

“…We have recently determined the IDS and PES of H 2 molecules interacting with helium atoms, allowing for high rotovibrational excitation of H 2 [7,8]. We have used these surfaces to compute the CIA spectra of H 2 interacting with He [8] and of D 2 interacting with He [9] over a wide range of temperatures. Here we use the same surfaces to compute the CIA spectrum of T 2 interacting with He.…”