Valence–shell electron energy-loss spectra of formic acid and acetic acid

Ari, Tayfun; Güven, Mehmet

doi:10.1016/s0368-2048(99)00084-5

Cited by 16 publications

(24 citation statements)

References 19 publications

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“…The vertical excitation energy of the first 20 states obtained with the FSCI and MOB-SCI calculations are presented in Table 1. The MOB-SCI calculation can reproduce well the results obtained with the FSCI calculation for the first few excited states and present a fair agreement with the results of the CASCI [28], couple cluster with singles and doubles (CCSD) [53], two-configuration electron-hole potential (TCEHP) [54] and the frozen core single excitation configuration mixing (FCSCM) [55] calculations and the electron energy-loss spectra (EELS) [56,57] found in Fig. 2 Schematic representation of the vertical excitation energies (in eV) of the 50 electronically excited states of formic acid obtained with the MOB-SCI calculation.…”

Section: Computational Detailssupporting

confidence: 67%

Electron collisions with formic acid

2021

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We report elastic, electronically inelastic, total ionization and total cross sections for the scattering of electrons by trans-formic acid. The calculations of the elastic and electronically inelastic cross sections were performed with the Schwinger multichannel method implemented with norm-conserving pseudopotentials. The electronically inelastic calculations were done within the minimal orbital basis for single configuration interaction approach with different multichannel coupling schemes considering from 1 up to 51 open channels, which enable us to study the influence of the multichannel coupling effects on the calculated cross sections. Polarization effects in the elastic channel were taken into account considering only the excitations related to the pairs used in the minimal orbital basis for single configuration interaction approach. We found that the magnitude of the elastic and inelastic cross sections decreases as more channels are treated as open in the scattering calculations. The calculated elastic differential cross sections present an overall good agreement with previous studies found in the literature. The elastic integral cross section presents a well-known π * shape resonance centered at 1.96 eV. The total ionization cross section was calculated with the binary-encounter-Bethe model and presents a good agreement with previous results from the literature. The total cross section was estimated using the calculated elastic, inelastic and ionization cross sections.

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Section: Computational Detailssupporting

confidence: 67%

Electron collisions with formic acid

2021

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“…However, the calculated and observed transition energies for the water are in good agreement: an extensive comparison is provided in our previous work . Experimental measurements place the first absorption band of formic acid in the energy range of 5.7–5.8 eV, which is in line with the transition energy of 5.66 eV computed in this work, as well as with the value of 5.96 eV calculated by Gruber‐Stadler et al When the character of this electronic excitation is considered, we assign it as an n(O 1 ), n(O 2 ) →

π_{O C O}^{*}

type transition, which is also in agreement with previous theoretical and experimental reports . These findings suggest that the electronic transition energies for the complexes predicted by our calculations would be good enough for the reliable prediction of the general characteristics of the transitions as well as the shifts of the absorption energies.…”

Section: Resultssupporting

confidence: 89%

“…The results are listed in Table and illustrated in Figure . For comparison, the lowest excited states for the isolated HOSO radical, water molecule and formic acid molecule along with available experimental data for the water molecule and formic acid are included in Table . Electronic excitations in formic acid and water require very high energy, and the transitions occur in the VUV region, well above those available from the sun in the troposphere.…”

Section: Resultsmentioning

confidence: 99%

Hydrogen bonding in the hydroxysulfinyl radical-formic acid-water system: A theoretical study

Tušar

Lesar

2016

J. Comput. Chem.

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Quantum chemical methods have been employed to evaluate the possible configurations of the 1:1 and 1:2 HOSO-formic acid complexes and 1:1:1 HOSO-formic acid-water complexes. The first type of complex involves two H bonds, while the other two types comprise three H bonds in a ring. The complexes are relatively stable, with CBS-QB3 computed binding energies of 14.3 kcal mol(-1) , 23.4 kcal mol(-1) , and 21.1 kcal mol(-1) for the lowest-energy structures of the 1:1, 1:2, and 1:1:1 complexes, respectively. Complex formations induce a large spectral red-shift and an enhancement of the IR intensity for the H-bonded OH stretching modes relative to those in the parent monomers. TDDFT calculations of the low-lying electronic excited states demonstrate that the complexes are photochemically quite stable in the troposphere. Small spectral shifts in comparison to the free HOSO radical suggest that the radical and the complexes would not be easily distinguishable using standard UV/vis absorption spectroscopy. © 2016 Wiley Periodicals, Inc.

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“…Finally, for the most oxidized sample, with CO 2 /CH 4 =4, the G5 band is most prominent as a consequence of the larger number of oxygenated bonds. G6 is a new band appearing at λ −1 ∼4.2 μm −1 (240 nm) and is assigned to the n O → CO * p transitions from the lone-pair orbital on the carbonyl oxygen to the antibonding π CO valence orbital (Barnes & Simpson 1963;Ari & Güven 2000) or to the valence shell excitations of hydroxyl groups (Duarte et al 2013). For this sample, the Figure 1.…”

Section: Vuv-visible Spectroscopymentioning

confidence: 96%

“…The assignment of these modes are provide in Table 3. We have deconvolved the main mid-infrared spectral bands of all samples prepared with a 95% N 2 concentration, corresponding to the following N 2 :CO 2 :CH 4 mixtures: 95:0:5, 95:2.5:2.5, Barnes & Simpson (1963); Ari & Güven (2000). Mutsukura (1999).…”

Section: Mid-infrared Spectroscopymentioning

confidence: 99%

Organic Aerosols in Anoxic and Oxic Atmospheres of Earth-like Exoplanets: VUV-MIR Spectroscopy of CHON Tholins

Gavilan

Carrasco

Hoffmann

et al. 2018

ApJ

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Organic hazes can drastically impact the characterization and detection of exoplanet atmospheres. We explore the effects of the transition from an anoxic to oxic atmosphere on the molecular structure of organic aerosols, by producing aerosols in N 2 :CO 2 :CH 4 -rich plasmas with increasing CO 2 /CH 4 gas ratios. We performed a spectroscopic study on the resulting aerosol analogs, CHON-rich tholins, from the vacuum-ultraviolet (VUV) to the mid-infrared (MIR), i.e., the 0.13-10 μm range. VUV spectroscopy revealed the presence of π-π * and n-π * transitions in the 200-500 nm range in all samples. These are attributed to electronic transitions in amine groups. As the CO 2 /CH 4 ratio increases, new bands emerge that can be attributed to electronic transitions in hydroxyl and carboxyl functional groups. MIR spectroscopy showed that the molecular structure of oxidized aerosols is dominated by the CO 2 /CH 4 ratio. Band deconvolution revealed the oxygenation of the organic matrix via the formation of oxygenated functional groups, including amide, hydroxyl, and carbonyl groups. For the most oxidized aerosols, absorption is greatest in the 0.13-0.3 μm and 6-10 μm regions. Some of the oxidized samples were further irradiated with VUV photons, resulting in the formation of π-π * bands in the 200-250 nm region and a decrease in the band intensities below 200 nm, attributed to amine and nitrile losses. We discuss how oxidized aerosols could provide a detectable (bio-)signature in exoplanet atmospheres.

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Valence–shell electron energy-loss spectra of formic acid and acetic acid

Cited by 16 publications

References 19 publications

Electron collisions with formic acid

Electron collisions with formic acid

Hydrogen bonding in the hydroxysulfinyl radical-formic acid-water system: A theoretical study

Organic Aerosols in Anoxic and Oxic Atmospheres of Earth-like Exoplanets: VUV-MIR Spectroscopy of CHON Tholins

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