An ab initio investigation of the infrared and visible-UV spectra of BN+, and photoionization spectrum of BN
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文摘
The low-lying quartet and doublet states of BN+ are reinvestigated theoretically by using multireference CI wavefunctions with a 6s5p3d1f basis set. The X 4Σ− ground state has a dissociation energy of 1.13 eV. The first excited state is2 Π (Te = 0.59 eV), with 1 2Σ− lying 0.11 eV higher. The infrared spectrum of X4 Σ− is characterized by very low absorption intensities (I 
8 km/mol for the fundamental absorption) and long emission lifetimes (4.9 s for v = 1 → v = 0). Franck-Condon factors, oscillator strengths (fv′v″) and radiative lifetimes (τv′) of the quartet-quartet transitions A 4Π−X 4Σ−, B 4Σ−−X 4Σ−, B 4Σ−−A 4Π and C 4Π−X4 Σ− are given. The strongest absorption band corresponds to B 4Σ−−X4 Σ−, with T00 = 3.81 eV and f00 = 0.0175. The longest lived quartet state is A 4Π, with τ0 
21 μs. The lifetimes of the B and C states (25 and 60 ns) are controlled by direct decay into the ground state rather than by cascading processes. The best estimate for the adiabatic ionization potential X 3Π(BN) → X 4Σ−(BN+) is 11.4 eV. A separation of 13.87 eV between X 4Σ−(BN+) and X 2Σ+(BN−), calculated atRe (BN+), agrees well with 13.8 ± 0.3 eV determined by charge inversion spectrometry. Finally, a model photoionization spectrum of BN is proposed to assist in the experimental characterization of the ground state of BN (whether 3Π or 1Σ+) via the 1 2Π state of BN+.
8 km/mol for the fundamental absorption) and long emission lifetimes (4.9 s for v = 1 → v = 0). Franck-Condon factors, oscillator strengths (fv′v″) and radiative lifetimes (τv′) of the quartet-quartet transitions A 4Π−X 4Σ−, B 4Σ−−X 4Σ−, B 4Σ−−A 4Π and C 4Π−X4 Σ− are given. The strongest absorption band corresponds to B 4Σ−−X4 Σ−, with T00 = 3.81 eV and f00 = 0.0175. The longest lived quartet state is A 4Π, with τ0 21 μs. The lifetimes of the B and C states (25 and 60 ns) are controlled by direct decay into the ground state rather than by cascading processes. The best estimate for the adiabatic ionization potential X 3Π(BN) → X 4Σ−(BN+) is 11.4 eV. A separation of 13.87 eV between X 4Σ−(BN+) and X 2Σ+(BN−), calculated atRe (BN+), agrees well with 13.8 ± 0.3 eV determined by charge inversion spectrometry. Finally, a model photoionization spectrum of BN is proposed to assist in the experimental characterization of the ground state of BN (whether 3Π or 1Σ+) via the 1 2Π state of BN+.