AbstractUsing laser‐induced fluorescence technique it is found that a third body is involved in the reaction with NO.

Photodissociation of NO has been investigated in the energy region between 8.89 eV, the energy required to produce N(2D)+O(3 P), and 9.26 eV, the ionization limit. Using the technique of resonance-enhanced multiphoton ionization (REMPI), we have demonstrated that there are areas in this energy region in which there are large yields of N(2D), and others where the yields are small. Localized concentrations, from 2-hν dissociation of NO at 270 nm, are an order of magnitude greater than can be obtained from a discharge in N2.

Although 248-nanometer radiation falls 0.12 electron volt short of the energy needed to dissociate O 2 , large densities of ozone (O 3 ) can be produced from unfocused 248-nanometer KrF excimer laser irradiation of pure O 2 . The process is initiated in some undefined manner, possibly through weak two-photon O 2 dissociation, which results in a small amount of O 3 being generated. As soon as any O 3 is present, it strongly absorbs the 248-nanometer radiation and dissociates to vibrationally excited ground state O 2 (among other products), with a quantum yield of 0.1 to 0.15. During the laser pulse, a portion of these molecules absorb a photon and dissociate, which results in the production of three oxygen atoms for one O 3 molecule destroyed. Recombination then converts these atoms to O 3 , and thus O 3 production in the system is autocatalytic. A deficiency exists in current models of O 3 photochemistry in the upper stratosphere and mesosphere, in that more O 3 is found than can be explained. A detailed analysis of the system as it applies to the upper atmosphere is not yet possible, but with reasonable assumptions about O 2 vibrational distributions resulting from O 3 photodissociation and about relaxation rates of vibrationally excited O 2 , a case can be made for the importance of including this mechanism in the models.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of isopropylthio radical with oxygen, nitrogen dioxide, and nitric oxide at 296 KGraham Black, Leonard E. Jusinski, and Roger PatrickCite this: J. Phys. Chem. 1988, 92, 5, 1134–1138Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://pubs.acs.org/doi/10.1021/j100316a026https://doi.org/10.1021/j100316a026research-articleACS PublicationsRequest reuse permissionsArticle Views26Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTResonance-enhanced multiphoton ionization measurements of atomic nitrogen(2D) quenching by atomic oxygen (3P)L. E. Jusinski, G. Black, and T. G. SlangerCite this: J. Phys. Chem. 1988, 92, 21, 5977–5982Publication Date (Print):October 1, 1988Publication History Published online1 May 2002Published inissue 1 October 1988https://pubs.acs.org/doi/10.1021/j100332a028https://doi.org/10.1021/j100332a028research-articleACS PublicationsRequest reuse permissionsArticle Views121Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

Iso-C3H7S radicals were generated by 248 nm photodissociation of i-C3H7SH and laser-induced fluorescence of the Ã-X̃ transition was studied in the 395–435 nm region. A prominent series of bands in the excitation spectrum is interpreted as transitions to levels of the C-S stretching mode in the excited state, which has a frequency of 347 ± 10 cm−1. Based on an expected radiative lifetime of about 800 ns, the observed zero-pressure lifetime of ≈ 120 ns suggests that all of the vibrational levels of the à state are strongly predissociated. Electronic quenching of i-C3H7S(Ã) is observed for a variety of collision partners.

N(2D) has been detected by resonance-enhanced multiphoton ionization (REMPI) at 269 nm in both the products of a microwave discharge in nitrogen (0.2–2%) in argon mixtures and as a result of two-photon dissociation of N2O. Further increase in the nitrogen fraction through the discharge decreased the N(2D) signal and finally replaced it with a series of molecular bands whose origin is thought to be electronically excited metastable states of N2.

A flowing afterglow in a 1% N2/Ar mixture at 10 Torr has been used as a source of N(2D), and resonance-enhanced multiphoton ionization (REMPI) at 269 nm has been used to follow the removal of the N(2D) by C2N2 and O2. The rate of removal by O2 is consistent with previous work. The rate coefficient for N(2D)/C2N2 interaction has been measured as (1.5±0.2) × 10−11 cm3 molecule−1 s−1 at 300 K, although the products have not yet been determined.

C2H5S radicals were generated by 248 nm photodissociation of C2H5SH and C2H5SSC2H5 and laser-induced fluorescence on the Ã-X̃ transition was studied. Prominent progressions are found in the C-S stretching mode which has a frequency of 408 ± 8 cm−1 in the excited state and 681 ± 15 cm−1 in the ground state. The 000 band head lies at 440.0 nm. All the bands are highly predissociated with the lifetime decreasing from 75 ns for the 000 band to ≈ 15 ns for the 306 band.

Resonance-enhanced photoionization has been used to follow S(3P2) in the photodissociation of CS2 at 193 nm. The contributions from initial photodissociation and from S(1D) relaxation have been resolved and give a (15±5)% yield of S(1D). The possibility of secondary production of S(3Pj) by CS photodissociation with a second 193 nm photon is discussed. Although this might raise the S(1D) yield to (26±8)%, production of S(3PJ) is still the dominant photodissociation channel.

Methylthio radicals (CH3S) have been generated by the 248 nm photodissociation of dimethyl disulphide [(CH3S)2] and 193 nm photodissociation of methylmercaptan [CH3SH]. Fluorescence has been excited on the Ã2A1â†�X2E transition. The transitions excited were 320 at 366.0 nm, 310 at 371.3 nm and 000 at 377.0 nm. Vibrational relaxation and electronic quenching of the upper state have been studied with a number of gases. By varying the delay between the excimer and dye laser pulses, it has also been possible to study vibrational relaxation in the ground state in the presence of the same gases. No reaction of the CH3S radical could be found with either O2 or O3(kO3⩽ 8 × 10–14 cm3 molecule–1 s–1), although the fast reaction with NO2 was confirmed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemiluminescent reactions in photodissociated cyanogen-oxygen mixturesG. Black, L. E. Jusinski, M. R. Taherian, T. G. Slanger, and D. L. HuestisCite this: J. Phys. Chem. 1986, 90, 26, 6842–6848Publication Date (Print):December 1, 1986Publication History Published online1 May 2002Published inissue 1 December 1986https://doi.org/10.1021/j100284a027Request reuse permissionsArticle Views14Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (738 KB) Get e-Alerts

Resonance-enhanced photoionization has been used to monitor the time evolution of S(3 3P2) produced by the interaction of S(3 1D2) with various gases. The S(3 3P2) signals have been used to calculate the branching ratios for quenching by these gases. The rate coefficients for reaction of S(3 3PJ) with O2, C2H4, and C3H6 were determined and used to correct the branching ratios for these gases.

F 2 (158-nm) and ArF (193-nm) excimer radiation has been used to photodissociate C 2 N 2 and produce chemiluminescence in C 2 N 2 –O 2 mixtures. In addition LIF measurements have followed the temporal behavior of the CN and NCO radicals. The behavior of CN is understood in terms of its reactions with O 2 and O. The NCO decay is controlled by radical or atom intermediates. This study has focused on the NO γ-band chemiluminescence and evidence is presented to support the view that it arises from energy transfer from N 2 ( A ) to NO and the N 2 ( A ) is made by the reaction N( 2 D ) + NCO → N 2 ( A ) + CO. An estimate of ≈25% is obtained for the N 2 ( A ) yield of this reaction, assuming a rate coefficient of 1 × 10 −10 cm 3 mor −1 s −1 (a lower rate would require a proportionately higher yield and vice versa).

S(1D) atoms have been produced by photodissociation of OCS at 248 nm and resonance-enhanced photoionization has been used to follow their decay. Rate coefficients for removing S(1D) have been determined for C2H4, C2H6, H2, CH4, N2O, OCS, CO2, N2, O2, and Ar at 300 K and upper limits determined for SF6, Ne, and He. (45±10)% of the collisions of S(1D) with OCS produce S(3P) atoms.

The absorption spectrum of O2 has been investigated at 930 K in the 1150–1300 Å region. Hot bands associated with ν″ = 1 in the ground state have been seen for each of the strong O2 bands observed over this wavelength range. The 1269 Å band, the identity of which has been somewhat controversial, is shown to be the 0–1 band of the B′3Σu−−X3Σg− transition.