Quantitative absorption and fluorescence spectroscopy of BCl3 in vacuum ultraviolet

The absorption and fluorescence cross sections and the fluorescence quantum yields of BCl3 were measured in the 106–190 nm region. A visible emission band appears at excitation wavelengths shorter than 173 nm and two ultraviolet emission bands appear at wavelengths shorter than 126.5 nm. Fluorescence spectra were dispersed to identify emitting species that are attributed to BCl*2. The upper limits of the potential energies for the observed emitting states are 2.56, 5.19, and 5.70 eV, as determined from the fluorescence thresholds. The photodissociation process of BCl3 is discussed in accord with the fluorescence observed. The radiative lifetimes of the visible band vary over the 5–24 μs range, and the quenching rate constants of the excited state by BCl3 vary in (1.2–2.7)×10−10 cm3/s, both depending on fluorescence wavelength.