Collisional relaxation of vibrational states of SrOH with He at 2 K

Abstract

Vibrational relaxation of strontium monohydroxide (SrOH) molecules in collisions with helium (He) at 2 K is studied. We find the diffusion cross section of SrOH at 2.2 K to be ${{\sigma }_{{\rm d}}}=(5\pm 2)\times {{10}^{-14}}\;{\rm c}{{{\rm m}}^{2}}$ and the vibrational quenching cross section for the (100) Sr–O stretching mode to be ${{\sigma }_{{\rm q}}}$ $\;=\;(7\pm 2)\times {{10}^{-17}}{\rm c}{{{\rm m}}^{2}}$ . The resulting ratio ${{\gamma }_{100}}$ $\;=\;{{\sigma }_{{\rm d}}}/{{\sigma }_{{\rm q}}}\sim 700$ is more than an order of magnitude smaller than for previously studied few-atom radicals (Au et al 2014 Phys. Rev. A http://dx.doi.org/10.1103/PhysRevA.90.032703 90 http://dx.doi.org/10.1103/PhysRevA.90.032703 ). We also determine the Franck–Condon factor for SrOH ( ${{\tilde{A}}^{2}}{{\Pi }_{1/2}}(100)\leftarrow {{\tilde{X}}^{2}}{{\Sigma }^{+}}(000)$ ) to be $(4.8\pm 0.8)\times {{10}^{-2}}$ .

Keywords

• buffer-gas cooling
• vibrational quenching
• cold polyatomic molecules