Recent experimental studies by Perreault et al. [J. Phys. Chem. Lett. 13, 10912 (2022)] have cast some doubts on the quality of the available interaction potentials for the He-${\mathrm{H}}_2$ complex. Perreault et al. investigated rotational quenching of HD and ${\mathrm{D}}_2$ prepared in the $v=2$ vibrational level and $j=2$ rotational level using the Stark-induced adiabatic Raman passage techniques. Experiments predicted a strong $l=2$ shape resonance near 1 K in the energy dependence of the $\mathrm{\Delta }j=-2$ rotational quenching rates for both systems, while quantum scattering calculations employing highly accurate interaction potentials predicted an $l=1$ resonance at energies lower than 1 K. To provide more insight into this process, we report here a detailed theoretical study of how the resonant features in the energy dependence of the cross section vary among three isotopologues: He-${\mathrm{H}}_2$, He-${\mathrm{D}}_2$, and He-${\mathrm{T}}_2$. Further, to explore how the resonance position is modified across these systems, we examine He-HX and He-XX collisions in which the mass of X is varied smoothly between the limiting cases of H and T, including realistic systems of HD, HT, and DT. Results are reported for both ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ collisions. Our calculations show that for the entire range of H-atom mass considered in our study, the $l=1$ resonance prevails and no dominant $l=2$ resonance exists, in agreement with previous theoretical studies on He-${\mathrm{H}}_2$, He-HD, and He-${\mathrm{D}}_2$ collisions.

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• Cold and ultracold molecules
• Cooling & trapping
• Scattering theory
• Ultracold collisions
• van der Waals interaction