2944-05-0Relevant articles and documents
Infrared laser kinetic spectroscopy of a photofragment CS generated by photodissociation of CS2 at 193 nm: Nascent vibrational-rotational- translational distribution of CS
Kanamori, Hideto,Hirota, Eizi
, p. 3901 - 3905 (1987)
Carbon monosulfide fragments generated by CS2 photodecomposition at 193 nm were examined by time-resolved observation of their vibration-rotation spectral lines with infrared diode laser kinetic spectroscopy.The CS molecules were found to be initially spread over a wide range of vibrational and rotational levels which were accessible with available energy, for both the triplet and singlet channels leading to sulfur atoms in the 3P ground and 1D excited states, respectively.The analysis of the observed line shape has allowed us to obtain information also on translational energy of CS fragments and to distinguish the contributions of the two channels.The branching ratio was thus estimated to be approximately one to one.
Jacox,Milligan
, p. 142,149 (1975)
Fast Flow Studies of Atomic Carbon Kinetics at Room Temperature
Dorthe, G.,Caubet, Ph.,Vias, Th.,Barrere, B.,Marchais, J.
, p. 5109 - 5116 (1991)
The reactions of atomic carbons with OCS, NO, O2, N2O, SO2, and H2S were studied at room temperature in a fast flow reactor.The atomic carbon, which was obtained from the microwave dissociation of CO diluted in He, was homogeneously mixed with the reactant molecules in a section of flow tube far from the discharge.The pseudo-first-order decay of atomic carbon was determined from the decay of CS ultraviolet chemiluminescence produced by the C + OCS reaction.As electronically excited CS is rather long-lived, it is shown how long-lived chemiluminescence can be used for obtaining kinetic data.In flow experiments, the rigorous determination of pseudo-first-order reaction rate constants is given by solving the differential continuity equation of the decaying reactive species in the flow.However, in most studies such an effort is not undertaken and rate constants are determined assuming plug flow for the reactive species because it allows an easy conversion of decay distances into reaction times.In the present study both approaches have been used.The plug-flow rate constant values were found to be significantly smaller than those given by the solution of the continuity equation.Our study thus provides a new example of the danger of the plug-flow approximation when conditions justifying it are not fulfilled.Specifically, the plug-flow assumption requires low homogeneous and wall-depletion rates of the reactive species with respect to its diffusion rate in the carrier gas.In our experiments none of these conditions was fulfilled and, in particular, the atomic carbon wall removal was found to be very efficient.Rate constants were determined for the first time for the reactions with OCS, SO2, and H2S.For the reactions with O2, NO, and N2O, previous studies, essentially performed by flash photolysis, gave a large scatter of data.Our values do not match any of those data.However agreement for relative rate coefficients is found with Husain's latest values, obtained at the lowest flash-lamp energy, which are furthermore the closest to ours.Our reaction rate constant values, given by the solution of the continuity equation of the atomic carbon in the flow, are (in 10-11 cm3 molecule-1 s-1 units): 10.1 +/- 0.7 with OCS; 2.7 +/- 0.2 with NO; 1.6 +/- 0.2 with O2; 0.85 +/- 0.16 with N2O; 6.9 +/- 1.7 with SO2; and 8.3 +/- 1.8 with H2S.
Gas-Phase Reactions of H3Si- and Me3Si-. The formation of Si-O and Si-S Bonds. A Flowing Afterglow and ab Initio Study
Sheldon, John C.,Bowie, John H.,DePuy, Charles H.,Damrauer, Robert
, p. 6794 - 6800 (1986)
The ions H3Si- and Me3Si- undergo Si-O and/or Si-S bond forming reactions with CO2, COS, CS2, SO2, N2O, MeNCO, and MeNCS forming H3SiO3-, Me3SiO-, H3SiS-, or Me3SiS- ions as appropriate.The rates of these reactions vary markedly, e.g., the reaction of H3Si- with CS2 (to form H3SiS- + CS) occurs at every encounter, whereas that of H3Si- with N2O (to form H3SiO- plus N2) occurs for only one in every thousand collisions.Ab initio calculations (at 6-31G level) for the reactions of H3Si- with CO2, CS2, SO2, and N2O suggest different and complex reaction pathways.The reaction of H3Si- with CO2 is characterized by initial approach to carbon, and subsequent rearrangements are required to form H3SiO-.H3SiS- is formed by a simple path from CS2 following initial attack at sulfur.H3Si- reacts with SO2 in alternative ways to form five-coordinate intermediate which subsequently decomposes to H3SiO- plus SO.H3Si- is likely to attack N2O at the terminal nitrogen, and subsequent rearrangement forms H3SiO-.The length, or complexity of the reaction pathway appears inversely related to the measured efficiency in the majority of reactions.
Photoionization dynamics in CS fragmented from CS2 studied by high-resolution photoelectron spectroscopy
Rijs, Anouk M.,Backus, Ellen H.G.,De Lange, Cornelis A.
, p. 744 - 749 (2004)
The photoionization dynamics of CS have been studied using high-resolution laser photoelectron spectroscopy. The photodissociation of CS2 at ～308 nm results in highly rotationally excited CS in its X 1∑+ singlet ground state, as well as in rotationally cold CS in the excited a3Π triplet state. The ground-state CS fragments are formed together with sulfur in its 3P, 1D, and 1S electronic states; triplet CS is produced in coincidence with ground-state sulfur (3P). In both channels the photoelectron spectra are dominated by Δν = 0 propensity, but transitions involving Δν = 1 and 2 are also observed.
Kawasaki, Masahiro,Sato, Hiroyasu,Kobayashi, Shuichiro,Arikawa, Tatsuo
, p. 101 - 105 (1988)
Production and IR absorption of cyclic CS2 in solid Ar
Bahou, Mohammed,Lee, Yu-Chang,Lee, Yuan-Pern
, p. 661 - 667 (2000)
Linear carbon disulfide (denoted as SCS) isolated in solid N2 or Ar at 13 K was irradiated with light at 193 nm from an ArF excimer laser. In addition to an absorption line of CS at 1277.4 cm-1, new lines at 881.3 and 520.9 cm-1 were observed after photolysis of SCS in solid N2. These lines are assigned to cyclic CS2 (denoted cyc-CS2) based on results from 34S- and 13C-isotopic experiments. Doublet lines of cyc-CS2 at 876.5 (881.1) and 517.7 (522.7) cm-1 were observed after irradiation of SCS in solid Ar at 193 nm; lines in parentheses are associated with a minor matrix site. Secondary photolysis at 248, 308, 532, 560, or 580 nm diminishes signals of cyc-CS2 and produces SCS. Theoretical calculations using MP2-full and density-functional methods (BLYP and B3LYP) predict three isomers of CS2: SCS, cyc-CS2, and linear CSS; relative energies, structures, vibrational wavenumbers, and IR intensities were predicted for each isomer. Cyc-CS2 has C-S bonds (~1.74 A) elongated relative to those of SCS (~1.56 A), a S-S bond ~2.14 A, and angleSCS ? 76°; it lies ~73 kcal mol-1 above SCS. Calculated vibrational wavenumbers, IR intensities, and isotopic shifts for cyc-CS2 fit satisfactorily with experimental results. An asymmetric transition State Connecting SCS and cyc-CS2 is characterized, yielding a ring-opening barrier of ~24.4 kcal mol-1 (zero-point energy corrected). Photoconversion between linear and cyclic CS2 in a matrix cage is discussed.
Energy distribution of the fragments produced by photodissociation of CS2 at 193 nm
Yang, S. C.,Freedman, A.,Kawasaki, M.,Bersohn, R.
, p. 4058 - 4062 (1980)
Gaseous CS2 was dissociated at 193 nm into CS and S.The translational and internal energy distributions of the CS fragments were measured.There is now overwhelming evidence that the upper electronic state S3 is predissociative.In fact there are three upper states of importance, the initially excited S3, a state which dissociates to CS(X1Σ) and S(1D) and a triplet state which dissociates to CS(X1Σ) and S(3P).The CS fragments were rotationally excited withy an average rotational energy ca.3.5 kcal/mole.The vibrational populations were also strongly inverted for both the 1D and the 3P dissociations and their surprisal plots were linear.CS fragments were found with v7.Of the dissociations resulting in CS fragments with v6, 80 +/-10percent of the S atoms are produced in the 1D state and 20 +/-10percent in the 3P state.
Matrix isolation and spectroscopic properties of the methylsulfinyl radical CH3(O)S
Reisenauer, Hans Peter,Romanski, Jaroslaw,Mloston, Grzegorz,Schreiner, Peter R.
supporting information, p. 9467 - 9469 (2013/10/01)
The atmospherically highly relevant methylsulfinyl radical CH 3(O)S was generated thermally under flash pyrolysis conditions and isolated in Ar matrices at 10 K; the allyl radical is a byproduct. CH 3(O)S and its D3- and 13C-isotopologues were characterized through the excellent agreement between experimental and computed IR and UV/Vis spectra.
Infrared absorption of gaseous ClCS detected with time-resolved Fourier-transform spectroscopy
Chu, Li-Kang,Han, Hui-Ling,Lee, Yuan-Pern
, p. 1 - 7 (2009/02/03)
A transient infrared absorption spectrum of gaseous ClCS was detected with a step-scan Fourier-transform spectrometer coupled with a multipass absorption cell. ClCS was produced upon irradiating a flowing mixture of Cl2 CS and N2 or C O2 with a KrF excimer laser at 248 nm. A transient band in the region of 1160-1220 cm-1, which diminished on prolonged reaction, is assigned to the C-S stretching (1) mode of ClCS. Calculations with density-functional theory (B3P86 and B3LYP/aug-cc-pVTZ) predict the geometry, vibrational wave numbers, and rotational parameters of ClCS. Therotational contour of the spectrum of ClCS simulated based on predicted rotational parameters agrees satisfactorily with experimental observati on; from spectral simulation, the band origin is determined to be at 1194.4 cm-1. Reaction kinetics involving ClCS, CS, and C S2 are discussed.
