The Mechanism of the HgH A22Π3/2 → X2Σ+ Emission in the Hg(63P0) Photosensitization of Hydrogen and the Alkanes

1973 ◽  
Vol 51 (8) ◽  
pp. 1207-1214 ◽  
Author(s):  
A. C. Vikis ◽  
D. J. Le Roy
Keyword(s):  
Ground State ◽  
Quantum Yields ◽  
Primary Process ◽  
Relative Quantum

The mechanism of the HgH A22Π3/2 → X2Σ+ emission detected in the Hg(63P0) photosensitized decomposition of H2 and some of the lower alkanes, RH, was investigated. It was concluded that ground state HgH was formed in the primary process Hg(63P0) + RH(or H2) → HgH(X2Σ+) + R(or H). The HgH A22Π3/2 → X2Σ+ emission and presumably the A12Π1/2 → X2Σ+ and B2Σ+ → X2Σ+ emission, also observed in the above systems, result from secondary excitation of ground state HgH on collision with Hg(63P0). Studies of the emission made possible the estimation of relative quantum yields for the above primary process.

Electronic spectroscopy of the transition of DCO and lifetimes and relative quantum yields of the state

2011 ◽  
Vol 270 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Steven J. Rowling ◽  
Scott A. Reid ◽  
Klaas Nauta ◽  
Scott H. Kable
Keyword(s):  
Electronic Spectroscopy ◽  
The State ◽  
Quantum Yields ◽  
Relative Quantum

PRIMARY PROCESS STUDIES BY MONOISOTOPIC PHOTOSENSITIZATION ON THE REACTIONS OF Hg 6(3P1) ATOMS WITH ALKYL CHLORIDES

1964 ◽  
Vol 42 (9) ◽  
pp. 2056-2064 ◽  
Author(s):  
J. K. S. Wan ◽  
O. P. Strausz ◽  
W. F. Allen ◽  
H. E. Gunning
Keyword(s):  
Mercury Vapor ◽  
Quantum Yields ◽  
Primary Process ◽  
Reaction Parameters ◽  
Specific Nature ◽  
Electrodeless Discharge ◽  
Discharge Source ◽  
Bond Scission ◽  
Decomposition Formula ◽  
Process Studies

The specific nature of the primary process in the reaction of 202Hg 6(3P1) atoms, photoexcited in natural mercury vapor by a cool 202Hg electrodeless discharge source, with CH3Cl has been examined in detail. Primary C–Cl bond scission occurs with unit efficiency. Quantum yields (φ) for the two primary modes of decomposition[Formula: see text]were found to have values of 0.71 (b) and 0.29 (a). The effect of various reaction parameters on the 202Hg enrichment in the calomel product has been investigated and the importance of isotopic mercury depletion in the reaction zone demonstrated by the use of intermittent illumination.A brief study of the reaction of ethyl, n-propyl, i-propyl, t-butyl, and n-amyl chlorides has revealed a relation between the molecular structure of the alleyl chloride and the efficiency of the monoisotopic route (a) to calomel formation. Thus, while the reactions of all the normal alkyl chlorides have φa values between 0.29 and 0.32, φa (isopropyl chloride) is only 0.22 and φa (t-butyl chloride) is 0.17.

Fluorescence lifetimes and relative quantum yields of 124-kilodalton oat phytochrome in water and deuterium oxide solutions

Biochemistry ◽  
1987 ◽  
Vol 26 (5) ◽  
pp. 1412-1417 ◽  
Author(s):  
Helmut Brock ◽  
Bela P. Ruzsicska ◽  
Tatsuo Arai ◽  
Wilhelm Schlamann ◽  
Alfred R. Holzwarth ◽  
...  
Keyword(s):  
Deuterium Oxide ◽  
Quantum Yields ◽  
Fluorescence Lifetimes ◽  
Relative Quantum

The photolysis of ozone by ultraviolet radiation. VI. Reactions of O( 1 D)

1972 ◽  
Vol 330 (1580) ◽  
pp. 131-146 ◽  
Keyword(s):  
Quantum Yield ◽  
Oxygen Carrier ◽  
Quantum Yields ◽  
Ozone Decomposition ◽  
Resonance Fluorescence ◽  
Significant Extent ◽  
Molecular Product ◽  
Relative Quantum ◽  
Carrier Gases ◽  
Made In

Tho reactions of O( 1 D) with O 3 , and with O 2 , have been studied by means of two essentially different techniques. Relative quantum yields for ozone decomposition after photolysis by λ = 254 nm radiation were measured by following changes in optical absorption. Relative concentrations of ground state oxygen atoms were measured by means of a resonance fluorescence technique. In both cases, measurements were made in the presence of O 2 , N 2 or He carrier gases in a flow system, at such time after photolysis that reactions involving O( 1 D) and O 2 ( 1 ∑ g + ) had gone to completion, whereas those involving O( 3 P) and O 2 ( 1 Δ g ) had not proceeded to a significant extent. The ‘intermediate’ quantum yields for ozone photolysis in helium and oxygen are 1.9 and 1.6 respectively, referred to an assumed intermediate quantum yield for photolysis in nitrogen of 1.0. In an oxygen carrier, for every ozone molecule decomposed in the primary step there results 1.5 ± 0.1 O( 3 P) atoms. For photolysis in helium this number is approximately 0.6. The results suggest that there are two pathways for the reaction between O( 1 D) and O 3 , in one of which the products are O 2 + 2O: two O atoms are formed on approximately one-third of reactive collisions. There is no evidence for production of an excited molecular product which is reactive on the concentration-time scale of these experiments. It is shown that both the intermediate quantum yield and the [O ( 3 P)] measurements are consistent with the formation of molecular oxygen in the 1 ∑ g + state on 50 to 60% of quenching collisions between O( 1 D) and O 2 .

Molecular Vibrations in the Exciton Theory for Molecular Aggregates. V. Electronic Spectra of Weakly-coupled Systems

1963 ◽  
Vol 16 (3) ◽  
pp. 315 ◽  
Author(s):  
EG McRae
Keyword(s):  
Electronic Spectra ◽  
Fluorescence Spectra ◽  
Vibrational Structure ◽  
Coupled Systems ◽  
Quantum Yields ◽  
Molecular Aggregates ◽  
Relative Quantum ◽  
Electronically Excited ◽  
Anthracene Crystal ◽  
Theoretical Results

The theory of the gross vibrational structure in the electronic spectra of molecular aggregates is developed for the case of weak intermolecular interaction. The electronically excited states are represented by a set of m-m functions corrected to first order as described in Part IV of this series. An explicit treatment is given for aggregates with two molecules per unit cell. Formulae are obtained for the relative vibronic intensities, splittings, and polarization ratios in absorption spectra, and for relative quantum yields and polarization ratios in fluorescence spectra. The theoretical results are compared with those of the E-V coupling theory developed in Parts II and III. On the basis of this comparison, a general equation is put forward to relate the theoretical crystal splitting (i.e. the splitting for a rigid model) to observed polarization ratios in spectra. The theoretical results are compared with the observed vibrational structure in the 3800 Ǻ band system of anthracene crystal. The crystal splitting calculated from the observed polarization ratios is 380 cm-1. The theory accounts, within the rather large experimental error, for the observed variations of polarization ratio in both the absorption and the fluorescence spectra of anthracene crystal.

Relative Quantum Yields for Anaerobic Photoassimilation of Glucose

Nature ◽  
1966 ◽  
Vol 212 (5060) ◽  
pp. 403-404 ◽  
Author(s):  
WOLFGANG WIESSNER
Keyword(s):  
Quantum Yields ◽  
Relative Quantum

Spectral properties and relative quantum yields of new fluorescent stains

1979 ◽  
Vol 2 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Anthony E. Bedrick ◽  
James L. Painter ◽  
Dagmar Lutringer Bonitz
Keyword(s):  
Spectral Properties ◽  
Quantum Yields ◽  
Relative Quantum ◽  
Fluorescent Stains

ABSORPTION, EMISSION AND NONLINEAR SPECTROSCOPIC CHARACTERIZATION OF REACTIVE DYE

2006 ◽  
Vol 15 (04) ◽  
pp. 481-490
Author(s):  
SHENG-LI GUO ◽  
ZHUN GUO ◽  
T. SUSDORF ◽  
TIAN-DE CAO
Keyword(s):  
Ground State ◽  
Nonlinear Optical ◽  
Spectroscopic Characterization ◽  
Reactive Dye ◽  
Mode Locking ◽  
Photon Absorption ◽  
Quantum Yields ◽  
Saturable Absorption ◽  
Potential Candidate ◽  
Reactive Orange

An optical spectroscopic characterization is carried out on a reactive dye (reactive orange 1). This dye is widely applied in textile coloration. It is a potential candidate for photonics applications. Its absorption cross-section spectra are measured. A fluorescence spectroscopic characterization is undertaken by measuring the fluorescence quantum distributions and fluorescence quantum yields. The saturable absorption is studied by nonlinear transmission measurements with intense picosecond laser pulses (second harmonic pulses of a mode-locked Nd :glass laser). The nonlinear optical absorption and refraction coefficients are measured by using the top-hat Z-scan technique at a wavelength of 532 nm with 35 ps duration pulses. Reactive orange 1 has the two-photon absorption coefficient of 1.20 cm/GW and the nonlinear refraction coefficient of -7.33 × 10-6 cm2/GW, respectively. In reactive orange 1, there occurs fast ground-state recovery by internal conversion likely via conical intersections. Low excited-state absorption and fast ground-state absorption recovery make it an ideal candidate for passive mode-locking of picosecond and femtosecond lasers as well as for fast nonlinear optical gating.

Collisional deactivation of singlet methylene in the photolysis of ketene

1969 ◽  
Vol 47 (18) ◽  
pp. 3345-3353 ◽  
Author(s):  
R. A. Cox ◽  
K. F. Preston
Keyword(s):  
Carbon Monoxide ◽  
Quantum Yield ◽  
Ground State ◽  
Inert Gases ◽  
Inert Gas ◽  
Quantum Yields ◽  
Electronic Relaxation ◽  
Excited Singlet ◽  
State Formula ◽  
Singlet Methylene

An investigation has been made into the effect of inert gas additions on product quantum yields for the photolysis at 2800 and 2490 Å of mixtures of ketene and oxygen and for the photolysis at 2800 Å of mixtures of ketene and carbon monoxide. Concentration ratios of O2 (or CO) to CH2CO were chosen so that the reaction of CH2(3Σg−) with CH2CO could be ignored and C2H4 formation could be attributed entirely to the reaction[Formula: see text]Quenching of the C2H4 quantum yield by inert gases was interpreted in terms of collisional deactivation of CH2(1A1) to the ground state[Formula: see text]and rate constant ratios k2/k1 have been determined for a number of gases: He (0.018), Ar (0.014), Kr (0.033), Xe (0.074), N2 (0.052), N2O (0.10), CF4 (0.047), C2F6 (0.11), and SF6 (0.045). It has been assumed that collision-induced intersystem crossover in excited singlet ketene makes an insignificant contribution to the observed quenching effects, but it has not been possible to verify this assumption experimentally. The mechanism of collision-induced electronic relaxation of singlet methylene is discussed in the light of the results.

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