研究目的
Investigating the interactions of cationic cobalt with carbon dioxide molecules using mass-selected infrared photodissociation spectroscopy and quantum chemical calculations.
研究成果
The combination of experimental and calculated IR spectra of [Co(CO2)n]+ (n=2?6) reveals that the CO2 molecules are weakly bound to the Co+ cations in an end-on configuration via a charge-quadrupole electrostatic interaction. The present finding is different from the previous IRPD spectroscopic study of rare gas-tagged [Co(CO2)n]+-Ar clusters with preferential formation of a core [Co(CO2)2]+ structure, indicating that the tagging of rare gas to the [Co(CO2)n]+ cluster is not innocent, but makes an obvious effect on the vibrational profiles.
研究不足
The technical and application constraints of the experiments include the insufficient photon fluence to induce photofragmentation of [Co(CO2)]+ under the present experimental conditions and the absence of the C?O stretch and the splitting feature of CO2 antisymmetric stretches from the experiment for some clusters.
1：Experimental Design and Method Selection:
The experiments were carried out on an IRPD instrument, which consisted of a laser vaporization supersonic cluster source, a tandem time-of-flight (TOF) mass spectrometer, and a tunable infrared laser source. The 532 nm output of a Nd:YAG laser was focused on vaporizing the rotating metal target. The [Co(CO2)n]+ complexes were produced by the reactions of the vaporized species with CO
2：Sample Selection and Data Sources:
The purities of the target was higher than
3：9%, and the surface of the target was polished prior to the experiments to ensure a clean vaporization target. The stagnation pressure of the reaction gas was approximately 5?8 atm and the gas was introduced into the vacuum region through a pulsed valve. List of Experimental Equipment and Materials:
The experimental setup included a laser vaporization supersonic cluster source, a tandem time-of-flight (TOF) mass spectrometer, and a tunable infrared laser source. The tunable infrared laser beam was generated by a KTP/KTA optical parametric oscillator/amplifier system (OPO/OPA, LaserVision) pumped by an injection-seeded Nd:YAG laser (Continuum Surelite EX).
4：Experimental Procedures and Operational Workflow:
After free expansion, all products were skimmed into the acceleration region and analyzed using the first stage of the TOF system. The cations of interest were mass-selected and decelerated into the extraction region of the vertical second stage of the TOF system. Here, a pulsed infrared laser was irradiated to the selected cationic packet in the acceleration region of the vertical second stage TOF mass spectrometer, which analyzed the dissociation fragments and the remaining parent cations.
5：Data Analysis Methods:
IRPD spectra were obtained by recording the fragment cations as a function of the tunable IR laser wavelength. The wavelength of the OPO laser output was calibrated using a commercial wavelength meter (Bristol, 821 Pulse Laser Wavelength Meter).
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