Optical spectra of Be atoms and Be2 molecules in rare gas matrices

Publisher Website
Google Scholar
Abstract
Beryllium atoms, trapped at 4 °K in solid neon, argon, and krypton, showed a strong absorption near 235 nm which is assigned to the resonance transition 1P1 ← 1S0 appearing at 234.86 nm (42 565 cm−1) in the gas phase. Specifically, the absorption occurred at 232.0 nm (43 090 cm−1), 236.0 nm (42 360 cm−1), and 240.5 nm (41 567 cm−1) in Ne, Ar, and Kr, respectively. Excitation to the 1P1 state also led to long‐lived emission in Ar and Kr matrices at 465.0 and 464.7 nm with lifetimes of 1.33(8) and 0.095(5) sec, respectively, and is assigned to the spin‐forbidden 3P1 → 1S0 emission. In each case an adjoining emission band also appeared at longer wavelengths, which can most probably be attributed to coupling of the electronic transition to matrix phonons. In concentrated matrices, Be2 molecular absorption yielded a progression of bands with the (0,0) band at 350.15(5) nm (28 551 cm−1) in Ne and at 361.30(5) nm (27 670 cm−1) in Ar. In analogy with the similar van der Waals molecules Mg2 and Ca2, these bands are assigned to the A 1Σ+u ← X 1Σ+g transition. The vibrational frequency in the upper state is 489 cm−1 in Ne and 474 cm−1 in Ar matrices. No other molecular electronic transitions were detected out to 50 000 cm−1.