Raman Chirped Adiabatic Passage Probed by X-ray Spectroscopy

Engin, Selma; Sisourat, Nicolas; Selles, P.; Taïeb, Richard; Carniato, S.

doi:10.1021/jp401125a

Cited by 4 publications

(7 citation statements)

References 31 publications

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“…The most recent ab initio calculation of the HCl cross section by Engin et al (2012) identifies 13 photoabsorbing electronically excited states of 1 Π and 1 Σ + symmetry below 12.2 eV, and is excellent in agreement with the previous computation of van for those states absorbing longer than 120 nm. Comparing the integrated cross section of Engin et al (2012) and the experimental data between 102 and 200 nm leads to agreement within 4%.…”

Section: Hcl -Hydrogen Chloridesupporting

confidence: 83%

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Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays

Bosman

Dishoeck

2017

A&A

422

442

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A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-ray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium abundances of abundant dark cloud abundances by up to a factor of two. The partial cross sections for H 2 O and NH 3 photodissociation forming OH, O, NH 2 and NH are also evaluated and lead to radiation-field-dependent branching ratios.

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Section: Hcl -Hydrogen Chloridesupporting

confidence: 83%

“…Comparing the integrated cross section of Engin et al (2012) and the experimental data between 102 and 200 nm leads to agreement within 4%. The excited states responsible for the significant HCl absorption between 91.6 and 102 nm are not well known.…”

Section: Hcl -Hydrogen Chloridementioning

confidence: 58%

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays

Bosman

Dishoeck

2017

A&A

422

442

View full text Add to dashboard Cite

show abstract

Section: Hcl -Hydrogen Chloridesupporting

confidence: 83%

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays,

Bosman,

van Dishoeck

2017

Preprint

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A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmicray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium abundances of abundant dark cloud abundances by up to a factor of two. The partial cross sections for H 2 O and NH 3 photodissociation forming OH, O, NH 2 and NH are also evaluated and lead to radiation-field-dependent branching ratios.

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“…2. [5][6][7] Owing to intramolecular Table 2 Selected geometrical parameters for the acetylacetone in the diketo form. As already shown in Table 3, the enolone is more stable with an energy of À0.46 eV (10.68 kcal mol À1 ).…”

Section: B Neb Resultsmentioning

confidence: 99%

“…However, the continuous progresses in intense and femtosecond mid-infrared laser technology [8][9][10][11] have opened the way for direct studies of photo-induced chemical reactions within the ground state. [5][6][7] Among the class of chemical reactions, proton-transfer processes are of prime importance in chemistry and biochemistry (ref. [5][6][7] Among the class of chemical reactions, proton-transfer processes are of prime importance in chemistry and biochemistry (ref.…”

Section: Introductionmentioning

confidence: 99%

Probing keto–enol tautomerism using photoelectron spectroscopy

Capron

Casier

Sisourat

et al. 2015

Phys. Chem. Chem. Phys.

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We theoretically investigate the mechanism of tautomerism in the gas-phase acetylacetone molecule. The minimum energy path between the enolone and diketo forms has been computed using the Nudged-Elastic Band (NEB) method within the density-functional theory (DFT) using the projector augmented-wave method and generalized gradient approximation in Perdew-Wang (PW91) parametrization. The lowest transition state as well as several intermediate geometries between the two stable tautomers have been identified. The outer-valence ionization spectra for all determined geometries have been computed using the third-order non-Dyson algebraic diagrammatic construction technique. Furthermore, the oxygen core-shell ionization spectra for these geometries have been obtained using DFT and the Becke three-parameter Lee-Yang-Parr (B3LYP) functional. It is shown that all spectra depend strongly on the geometries demonstrating the possibility of following the proton-transfer dynamics using photoelectron spectroscopy in pump-probe experiments.

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Raman Chirped Adiabatic Passage Probed by X-ray Spectroscopy

Cited by 4 publications

References 31 publications

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Probing keto–enol tautomerism using photoelectron spectroscopy

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