Knowledge Bank

Electronic transitions have been observed with LIF techniques in a supersonic molecular beam of He doped with $H2$ and $D2$ and laser-ablated Rh vapor. Bands of RhH have been found near 464.73 and 438.38 nm, which are assigned as (0,0) and (1,0) vibrational bands of a $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta 3-X3\Delta 3$ electronic transition. There is a sudden disapperance of the rotational structure in the (1,0) band of RhH above $J\prime =7$ and the spectra associated with higher vibrational levels in the excited states are missing. These observations are attributed to predissociation. Its onset agrees with an ab intio calculation of $22664-23955cm-1a$ and the estimate of $20650\pm 1750cm-1$ from $thermochemistry.b$ The RhH(0,0) band also shows irregular A-doubling. The corresponding (0,0) and (1,0) transitions in RhD appear at 463.40 and 443.02 nm. Analyses of the spectra indicate that the ground state of RhH is an inverted $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta$ state, which is believed to derive from the electronic configuration $\dots \delta 3\pi 1\sigma 1$ and provide the following RhH molecular constants($cm-1:B0\prime \prime =6.546[r0\prime \prime =0.1610nm],B0\prime =6.175,B1\prime =5.823,\omega e\prime \prime =1927,\omega e\prime \prime xe\prime \prime =35.7,\omega e\prime =1645,\omega e\prime xe\prime =174$. The observed ground state symmetry and internuclear distance agree with ab initio $predictions.a$ Six additional bands have been found for RhD: near $445.15nm(\Omega \prime =3-\Omega \prime \prime =3),428.05nm(\Omega \prime =3-\Omega \prime \prime =3)427.83nm(\Omega \prime =3-\Omega \prime \prime =3),424.40nm(\Omega \prime =2-\Omega \prime \prime =3),422.58nm(\Omega \prime =3-\Omega \prime \prime =3),$ and $409.24nm(\Omega \prime =4-\Omega \prime \prime =3)$.