Analysis of the High-Resolution Rotational Structure of the Origin and First Torsional Members of the 267-nm Band System of Formic Acid

Beaty-Travis, Leanne M.; Moule, D. C.; Liu, Haisheng; Lim, E. C.; Judge, R. H.

doi:10.1006/jmsp.2000.8253

Cited by 5 publications

(2 citation statements)

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“…Experimentally, the band origin has been identified as 37413.4 cm -1 (107.0 kcal·mol -1 ) in the S 0 → S 1 spectrum of gas-phase formic acid . In aqueous solution, the absorption maximum was located at 207 nm by femtosecond transient absorption spectroscopy, which is blue shifted by ∼8 nm (∼0.2 eV) relative to the peak position of the gas-phase spectrum .…”

Section: Resultsmentioning

confidence: 97%

Solvent Effects on the Photodissociation of Formic Acid: A Theoretical Study

Tian

Fang

2006

J. Phys. Chem. A

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Photodissociation of aqueous formic acid has been investigated with the CASSCF, DFT, and MR-CI methods. Solvent effects are considered as a combination of the hydrogen-bonding interaction from explicit H2O molecules and the effects from the bulk surrounding H2O molecules using the polarizable continuum model. It is found that the hydrogen-bonding effect from the explicit water in the complex is the major factor to influence properties of aqueous formic acid, while the bulk surrounding H2O molecules has a noticeable influence on the structures of the complex. The direct C-O bond fission along the S1 pathway is predicted to be an important channel upon photolysis of aqueous formic acid at 200 nm, which is consistent with experimental observation that aqueous formic acid dissociates predominantly into fragments of HCO and OH. The existence of a dark channel upon photolysis of aqueous formic acid at 200 nm is assigned as fast relaxation from the S1 Franck-Condon geometry to the T1/S1 intersection and subsequent S1-->T1 intersystem crossing process. S1-->S0 internal conversion followed by molecular elimination to CO+H2O is the most probable primary process for formation of carbon monoxide, which was observed with considerable yield upon photolysis of aqueous formic acid at 253.7 nm.

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Section: Resultsmentioning

confidence: 97%

Solvent Effects on the Photodissociation of Formic Acid: A Theoretical Study

Tian

Fang

2006

J. Phys. Chem. A

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“…The OCO bend mode has been observed, and activity in this mode arises because of the planar-to-pyramidal geometry change occurring upon photon absorption. After these early studies, rotational and infrared spectra of formic acid at both low and high resolution have been extensively investigated by Baskakov, − Tan, , Moule, and Judge. , All of the fundamentals have been assigned, and the band origin has been accurately identified as 37 413.4 cm -1 in the S 0 → S 1 spectrum.…”

Section: Introductionmentioning

confidence: 99%

A CASSCF/MR-CI Study toward the Understanding of Wavelength-Dependent and Geometrically Memorized Photodissociation of Formic Acid

Fang

2003

J. Am. Chem. Soc.

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The S(0), T(1), and S(1) potential energy surfaces for the HCOOH dissociation and isomerization processes have been mapped with different ab initio methods. The wavelength-dependent mechanism for the HCOOH dissociation was elucidated through the computed potential energy surfaces and the surface crossing points. The HCOOH molecules in S(1) by excitation at 248 nm mainly decay to the ground state via the S(0) and S(1) vibronic interaction, followed by molecular eliminations in the ground state. The S(1) direct dissociation to HCO((2)A') + OH((2)Pi) is the dominant pathway upon photoexcitation at 240-210 nm. Meanwhile, there is a slight probability that the system relaxes to the ground state via the S(0) and S(1) vibronic interaction at these wavelengths. After irradiation of HCOOH at 193 nm, the S(1) direct dissociation into HCO((2)A') + OH((2)Pi) is energetically the most favorable pathway. In view of high IC efficiency at the S(0)/S(1) conical crossing, the S(1) --> S(0) internal conversion via the S(0)/S(1) point can occur with considerable efficiency. In addition, the S(1) isomerization probably plays a dominant role in the partially conformational memory of the HCOOH photodissociation, which has been discussed in detail.

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