Knowledge Bank

Electronic quenching cross sections of BH $(A1\Pi )$ were measured by examining fluorescence decay times in the presence of sixteen collision partners at 298K. The partners exhibit wide variations in mass, electric dipole moment and higher order moments. Except for the extremely low cross sections measured for He and $SF6$, values range from 5 to $150\backslash AA2$. Of the fourteen remaining partners, eleven are represented moderately well by a multipole attractive force model, two (OCS and $CH2F2$) fall well below the expected cross section and one ($CHFCl2$) has an experimental cross section larger than predicted by this model. A temperature comparison is made for the quenching of $BH(A1\Pi )$ by CO at 298K and 473K. The measured rate constant at 473K exhibits a 10% decrease compared to the 298K value with an uncertainty of 11%.