Chemiluminescence spectra of thioformaldehyde and selenoformaldehyde

Glinski, Robert J.; Taylor, C D; Martin, Harold R.

doi:10.1021/j100169a021

Cited by 16 publications

(15 citation statements)

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“…They used a planar ground state geometry with bond lengths that, to within 0.1 pm, are identical to ours. 8 In their search for chemiluminescence of telluroformaldehyde in reactions of ͑CH 3 ͒ 2 Te with F 2 -in view of similarity with the sulphur and selenium systems-Glinski et al 8 failed to detect any emission from the H 2 CTe molecule. Our response approach is to be interpreted as a complete summation over the residual of the excited states and leads to a calculated radiative lifetime ͑about 30-50 ms, see Table II͒ that is consistent with the laser-induced phosphorescence of selenoformaldehyde 4,7 and with the comparative study of chemiluminescence spectra of H 2 CS and H 2 CSe.…”

Section: Resultsmentioning

confidence: 99%

“…The S 0 -T 1 spectra in the H 2 CX molecules have been exhaustively studied with high resolution [2][3][4][5][6][7][8] in spite of the fact that formaldehyde is the only chemically stable species in this series. The S 0 -T 1 spectra in the H 2 CX molecules have been exhaustively studied with high resolution [2][3][4][5][6][7][8] in spite of the fact that formaldehyde is the only chemically stable species in this series.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of low-scaling methods for calculation of phosphorescence parameters

Jansson

Norman

Minaev

et al. 2006

The Journal of Chemical Physics

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In order to find a methodology that is a compromise between favorable computational scaling and tolerable errors, a series of nonrelativistic approaches for the calculation of radiative phosphorescence lifetimes are benchmarked against fully relativistic four-component results. The study of the a 3A2-X 1A1 transition intensity in the series of H2CX molecules, where X is a chalcogene atom, X={O,S,Se,Te}, indicates a general good agreement between fully relativistic four-component and nonrelativistic perturbation-theoretical calculations. Among the nonrelativistic approaches, the scaled-charge spin-orbit operator approach is recognized as to provide transition matrix elements that are in good agreement with those obtained with the more elaborate Breit-Pauli and atomic mean field spin-orbit operators. This finding supports phosphorescence calculations using the available linear scaling technology for large complexes and, together with effective-core potentials, large complexes including heavy elements.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of low-scaling methods for calculation of phosphorescence parameters

Jansson

Norman

Minaev

et al. 2006

The Journal of Chemical Physics

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“…Selenoformaldehyde (X A 1 1 ) is the global minimum on the ground electronic state PES of the [H,H,C,Se] species. Despite several experimental[28][29][30][31][32] and first-principles 32-37 studies, characterization of this PES received less attention than that of [H,H,C,S]. Following the first successful preparation of selenoformaldehyde in the gas phase 38 , Collins et al33 reported HF and limited electron correlation results on the electronic structure of H 2 C=Se.…”

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confidence: 99%

Do the mercaptocarbene (H–C–S–H) and selenocarbene (H–C–Se–H) congeners of hydroxycarbene (H–C–O–H) undergo 1,2-H-tunneling?

Sarka

Császár

Schreiner

2011

Collect. Czech. Chem. Commun.

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Dedicated to our colleague Zdeněk Havlas for his contributions to computational chemistry and on the occasion of his 60th birthday.The principal purpose of this investigation is the determination of the tunneling half-lives of the trans-HCSH → H 2 CS and the trans-HCSeH → H 2 CSe unimolecular isomerization reactions at temperatures close to 0 K. To aid these determinations, accurate electronic structure computations were performed, with electron correlation treatments as extensive as CCSDT(Q) and basis sets as large as aug-cc-pCV5Z, for the isomers of [H,H,C,S] and [H,H,C,Se] on their lowest singlet surfaces and for the appropriate transition states yielding structural data for key stationary points characterizing the isomerization reactions. The computational results were subjected to a focal-point analysis (FPA) that yields accurate relative energies with uncertainty estimates. The tunneling half-lives were determined by a simple Eckart-barrier approach and via the more sophisticated though still one-dimensional Wentzel-KramersBrillouin (WKB) approximation. Only stationary-point information is needed for the former while an intrinsic reaction path (IRP) is necessary for the latter approach. Both protocols suggest that, unlike for the parent hydroxymethylene (HCOH), at the low temperatures of matrix isolation experiments no tunneling will be observable for the trans-HCSH and trans-HCSeH systems.

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“…[l, 21). The observed current ( j ) may be attributed to a succession of events: a) the absorption of light (characteristic quantities: incident light intensity I , and absorption coefficient x), b) the creation and diffusion of an exciton (diffusion coefficient D and diffusion length l,), c) the reabsorption and light guide effects [3], d) the impact of an exciton on the active surface (surface annihilation constant s), e) the dissociation of the exciton to produce a carrier pair, f) the separation of the carrier pair (the latter two processes characterized by the overall injection yield y). All these 300 320 340 360 380 400 300 320 340 360 380 400 (4) with the following parameters: a) qs/(l + Ds/sslDS) = 2 x and b) 5.6 x 10-obtained from j , with AEl = 0 and I , , = 50 nm determined from the experimental plot of Fig.…”

Section: Introductionmentioning

confidence: 99%

“…In the case of anthracene crystals holes are produced by excitons striking an anthracenel metal [l, 2, 4, 51 or anthracene/electrolyte [3,6 to 151 interface. According to (1) the injection-limited hole current is connected with absorption in such a way that j ( 2 ) follows .…”

Section: Introductionmentioning

confidence: 99%

Energy‐Dependent Excitonic Injection of Charge into Anthracene Crystals

Strzelecka

Godlewski

Kalinowski

1992

Physica Status Solidi (b)

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Steady-state exciton-injection currents (EIC) as a function of electric field and temperature are measured in anthracene crystals upon energy-selective excitation within the So + S, transition. The current for each given absorption coefficient decreases as the excitation energy (ho) passes through the high-energy wing and is swept downward the low-energy wing (Urbach tail) of the absorption band, demonstrating that the flux of excitons reaching the injecting contact is energy dependent. The maximum absorption at the So + S, 0-0 transition establishes a demarcation energy ha,. Above hw, only diffusion of mobile (band) excitons (S) is an injection-determining process, below faw, thermal activation of localized states (SJ becomes an unavoidable step in the S-exciton creation process, diminishing the effective flux of S-excitons reaching the contact. An analysis of the dependence of the activation energy on the localization energy hw, -hm of primarily excited S, states indicates that EIC are the sum of a singlet exciton-injection contribution and a triplet exciton-injection contribution, the triplets being produced via intersystem crossing transitions from S and S, states. A theoretical description of excitonic processes underlying charge injection is presented and applied to the experimental results. Agreement between theoretical predictions and experiment is good if the frequency factor for the thermally activated S , -+ S excitation is assumed to be z lo9 s -'.Stationare Exzitoneninjektionsstrome (EIC) werden in Abhangigkeit vom e1ektri:chen Feld und der Ternperatur in Anthrazenkristallen unter energieselektiver Anregung im So .+ S,-Ubergang gemessen. Fur jeden vorgegebenen Absorptionskoeffizienten nimmt der Strom ab, wenn die .Anregungsenergie ho im hochenergetischen oder im niederenergetischen (Urbach-Auslauier) Fliigel des Absorptionsbandes liegt, was zeigt, dalj der den injizierenden Kontakt erreichende Exzitonenflu5 energieabhangig ist. Das Absorptionsmaximum am 0-0 So -+ S,-ubergang legt eine Energiemarkierung hoo fest. Oberhalb hw, bestimmt nur die Diffusion beweglicher (Band)-Exzitonen S den Injektionsprozelj, unterhalb hw, ist thermische Aktivierung von lokalisierten Zustanden S, ein unausweichlicher Schritt im Prozelj der S-Elektronenbildung, wodurch der effektive Flu13 der den Kontakt erreichenden S-Exzitonen verringert wird. Eine Analyse der Abhangigkeit der Aktivierungsenergie von der Lokalisierungsenergie hwo -hw der primar angeregten S,-Zustande zeigt, dalj die EIC sich aus einem Singulett-und einem Triplett-Exzitoninjektionsanteil zusammensetzen, dabei entstehen die Triplets durch Intersystem-Crossing aus S und S,-Zustlnden. Die der Ladungsinjektion zugrundeliegenden Exzitonenprozesse werden theoretisch beschrieben und auf experimentelle Ergebnisse bezogen. Die obereinstimmung von Theorie und Experiment ist gut, wenn der Frequenzfaktor fur die thermisch aktivierte S, + S-Anregung zu z lo9 s -l angenommen wird.

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Chemiluminescence spectra of thioformaldehyde and selenoformaldehyde

Cited by 16 publications

References 0 publications

Evaluation of low-scaling methods for calculation of phosphorescence parameters

Evaluation of low-scaling methods for calculation of phosphorescence parameters

Do the mercaptocarbene (H–C–S–H) and selenocarbene (H–C–Se–H) congeners of hydroxycarbene (H–C–O–H) undergo 1,2-H-tunneling?

Energy‐Dependent Excitonic Injection of Charge into Anthracene Crystals

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