The far-ultraviolet spectra of some simple alcohols and fluoroalcohols

Salahub, D. R.; Sándorfy, C.

doi:10.1016/0009-2614(71)80578-x

Cited by 95 publications

(64 citation statements)

References 8 publications

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“…The largest rate we find is for the dissociation of C 3 , with a 5-fold increase relative to Gredel et al (1989), due to the addition of a previously-unknown and strong C 3 absorption channel at 160 nm as computed by van Hemert & van Dishoeck (2008) and seen in the laboratory by Monninger et al (2002). The new CH 3 OH dissociation and ionisations rates are 2.5 times smaller than that calculated by Gredel et al (1989), who employed very similar cross sectional data (Harrison et al 1959;Salahub & Sandorfy 1971) over the range 120 to 215 nm. Additional information described in Sect.…”

Section: Resultsmentioning

confidence: 53%

“…Two measurements spanning the wavelength ranges 120 to 208 nm (Salahub & Sandorfy 1971) and 30 to 120 nm (Koizumi et al 1986) were combined into a single photoabsorption cross section. An absolute ionisation cross section between 125 and 107 nm is measured by ion mass-spectroscopy (Cool et al 2005), and a photoionisation cross section constructed by supplementing this with a measured photoionisation efficiency between 76 and 92 nm (Hatano 1999).…”

Section: H 7 Oh -1-propanolmentioning

confidence: 99%

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Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays

Bosman

Dishoeck

2017

A&A

425

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: Resultsmentioning

confidence: 53%

Section: H 7 Oh -1-propanolmentioning

confidence: 99%

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays

Bosman

Dishoeck

2017

A&A

425

442

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“…A beam splitter allowed the simultaneous recording (on a reference photodiode) of incident light intensity, I 0 . Literature values (in 10 −19 cm 2 molecule −1 ) of σ X =6.65 and 11.8 (Dillon et al, 2005), 22.0 (Salahub and Sandorfy, 1971), and 30.1 (Gierczak et al, 2003) were used to determine concentrations for respectively X=CH 3 OH, C 2 H 5 OH, (CH 3 ) 2 CHOH and CH 3 C(O)CH 3 via the Beer-Lambert relationship, Eq. (1).…”

Section: Reagent Handling and Concentration Measurementsmentioning

confidence: 99%

Direct detection of OH formation in the reactions of HO2 with CH3C(O)O2 and other substituted peroxy radicals

2008

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Abstract. This work details the first direct observation of OH as a product from (R1): HO 2 +CH 3 C(O)O 2 →(products), which has generally been considered an atmospheric radical termination process. The technique of pulsed laser photolysis radical generation, coupled to calibrated laser induced fluorescence detection was used to measure an OH product yield for (R1) of α 1 (298 K)=(0.5±0.2). This study of (R1) included the measurement of a rate coefficient k 1 (298 K)=(1.4±0.5)×10 −11 cm 3 molecule −1 s −1 , substantially reducing the uncertainties in modelling this important atmospheric reaction. OH was also detected as a product from the reactions of HO 2 with three other carbonylcontaining peroxy radicals, albeit at smaller yield, e.g. (R2): HO 2 +CH 3 C(O)CH 2 O 2 →(products), α 2 ≈0.15. By contrast, OH was not observed (α<0.06) as a major product from reactions where carbonyl functionality was absent, e.g. HO 2 +HOCH 2 CH 2 O 2 (R8), and HO 2 +CH 3 CH(OH)CH 2 O 2 (R9).

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“…Most of the spectroscopic studies have been mainly focused on the determination of the energies of their electronically excited states. Concerning the spectral intensities, photoabsorption measurements of ethanol have been performed by several experimentalists using emission line sources [7][8][9], synchrotron radiation sources [5,10] and high-resolution dipole (e,e) spectroscopy [11] in the vacuum ultraviolet region covering from 5 to 32 eV. By contrast, photoionization cross-section data are scarce.…”

Section: Introductionmentioning

confidence: 99%

Photoionization cross sections and asymmetry parameters for ethanol. A theoretical study

Velasco

Lavín

2016

Journal of Quantitative Spectroscopy and Radiative Transfer

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Photoionization cross-sections and asymmetry parameters for the outermost orbital of ethanol has been determined with the Molecular Quantum Defect Orbital (MQDO) method. The individual ionization cross-sections corresponding to the Rydberg series that constitute the ionization channels for the production of the molecular cation in its ground state are reported. Good agreement has been found with the experiment for the photoionization cross-sections. To our knowledge, predictions of the asymmetry parameter for the ethanol are made here for the first time. It is hoped the MQDO data will be useful in combustion chemistry and astrophysics.

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The far-ultraviolet spectra of some simple alcohols and fluoroalcohols

Cited by 95 publications

References 8 publications

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Direct detection of OH formation in the reactions of HO<sub>2</sub> with CH<sub>3</sub>C(O)O<sub>2</sub> and other substituted peroxy radicals

Photoionization cross sections and asymmetry parameters for ethanol. A theoretical study

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The far-ultraviolet spectra of some simple alcohols and fluoroalcohols

Cited by 95 publications

References 8 publications

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Direct detection of OH formation in the reactions of HO&lt;sub&gt;2&lt;/sub&gt; with CH&lt;sub&gt;3&lt;/sub&gt;C(O)O&lt;sub&gt;2&lt;/sub&gt; and other substituted peroxy radicals

Photoionization cross sections and asymmetry parameters for ethanol. A theoretical study

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Direct detection of OH formation in the reactions of HO<sub>2</sub> with CH<sub>3</sub>C(O)O<sub>2</sub> and other substituted peroxy radicals