A high-resolution photoelectron imaging and theoretical study of CP− and C2P−

Abstract

The discovery of interstellar anions has been a milestone in astrochemistry. In the search for new interstellar anions, CP and CP are viable candidates since their corresponding neutrals have already been detected astronomically. However, scarce data exist for these negatively charged species. Here we report the electron affinities of CP and CP along with the vibrational frequencies of their anions using high-resolution photoelectron imaging. These results along with previous spectroscopic data of the neutral species are used further to benchmark very accurate quartic force field quantum chemical methods that are applied to CP, CP, CP, and two electronic states of CP. The predicted electron affinities, vibrational frequencies, and rotational constants are in excellent agreement with the experimental data. The electron affinities of CP (2.8508 ± 0.0007 eV) and CP (2.6328 ± 0.0006 eV) are measured accurately and found to be quite high, suggesting that the CP and CP anions are thermodynamically stable and possibly observable. The current study suggests that the combination of high-resolution photoelectron imaging and quantum chemistry can be used to determine accurate molecular constants for exotic radical species of astronomical interest.

Probing the coupling of a dipole-bound electron with a molecular core

“…More experimental details are provided in the ESI †. The non-resonant PE spectra of C 2 P – have been discussed in detail previously39 and they serve as the reference for the resonant PES in the current study. Additional non-resonant PE spectra have been measured in the current work at 2.6360, 2.6588, and 2.7454 eV, as compared with the 2.9025 eV spectrum reported previously in Fig.…”

“…, the C–C stretching ( ν 1 ), C–P stretching ( ν 2 ), and the bending mode ( ν 3 ) ‡‡The vibrational modes were labeled inadvertently according to decreasing frequencies (1 for C–C stretching, 2 for C–P stretching, and 3 for bending) in ref. 39.…”

“…The dipole moment of C 2 P was calculated to be 3.241 D,38 which is large enough to support a DBS. We have recently reported the PE spectra of C 2 P – and measured the electron affinity (EA) of C 2 P to be 2.6328 ± 0.0006 eV 39. The valence electron configuration of the C 2 P – anion is 4σ 2 5σ 2 6σ 2 2π 4 7σ 2 3π 2 with the 3 Σ + electronic ground state 39.…”

“…We have recently reported the PE spectra of C 2 P – and measured the electron affinity (EA) of C 2 P to be 2.6328 ± 0.0006 eV 39. The valence electron configuration of the C 2 P – anion is 4σ 2 5σ 2 6σ 2 2π 4 7σ 2 3π 2 with the 3 Σ + electronic ground state 39. Hence, C 2 P – is expected to possess a dipole-bound excited state with an excitation energy slightly below 2.6328 eV by promoting an electron from the 3π orbital to a dipole-bound orbital.…”

High resolution photoelectron imaging of boron-bismuth binary clusters: Bi2Bn− (n = 2–4)

“…The experiments were conducted using a high resolution PE imaging apparatus coupled to a laser vaporization supersonic cluster source, which has been described in detail previously. [36][37][38][39] Briefly clusters were produced by focusing the second harmonic of a Nd:YAG laser onto a disk target made of a mixture of Bi and isotopically enriched 10 B powders. The laser-induced plasma formed inside the nozzle was cooled by a helium carrier gas seeded with 10% argon to initiate nucleation.…”