Mihaela Deselnicu

Fluorescence excitation and emission spectroscopy of the ÃA″1←X̃A′1 system of CHBr

We report fluorescence excitation and emission spectra of CHBr in the 450–750nm region. A total of 30 cold bands involving the pure bending levels 20n with n=2–8 and combination bands 20n301(n=1–8), 20n302(n=1–6), 20n303(n=1–2), 10120n(n=5–7), 10120n301(n=4–6), and 10120n302(n=5) in the AA″1←XA′1 system were observed, in addition to a number of hot bands. The majority of these are reported and/or rotationally analyzed here for the first time. Spectra were measured under jet-cooled conditions using a pulsed discharge source, and rotational analysis yielded band origins and rotational constants for both bromine isotopomers (CHBr79,CHBr81). The derived AA″1 vibrational intervals are combined with results of [Yu et al. J. Chem. Phys. 115, 5433 (2001)] to derive barriers to linearity for the 2n, 2n31, and 2n32 progressions. The AA″1 state C–H stretching frequency is determined here for the first time, and the observed ν3 dependence of the Br79–Br81 isotope splitting in the AA″1 state is in good agreement ...

Electronic spectroscopy of the ÃA″1↔X̃A′1 system of CDBr

We report fluorescence excitation and single vibronic level emission spectra of jet-cooled CDBr in the 450–750nm region. A total of 32 cold bands involving the pure bending levels 20n with n=3–10 and combination bands 20n301 (n=2–10), 20n302 (n=2–9), 10120n (n=7–10), and 10120n301 (n=6,8–9) in the AA″1←XA′1 system of this carbene were observed; most of these are reported and/or rotationally analyzed here for the first time. Rotational analysis yielded band origins and effective (B¯) rotational constants for both bromine isotopomers (CD79Br and CD81Br). The derived AA″1 vibrational intervals are combined with results of Yu et al. [J. Chem. Phys. 115, 5433 (2001)] to derive barriers to linearity for the 2n, 2n31, and 2n32 progressions. The AA″1 state C–D stretching frequency (2350cm−1) is determined for the first time, in excellent agreement with theory, as are the Br79–Br81 isotope splittings in the excited state. Our emission spectra probe the vibrational structure of the XA′1 and aA″3 states up to ...