scholarly journals Reactions of thiyl radicals. III. Photochemical equilibrium in the photolysis of liquid disulfide mixtures

1968 ◽  
Vol 46 (6) ◽  
pp. 999-1003 ◽  
Author(s):  
K. Sayamol ◽  
A. R. Knight
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Incident Radiation ◽  
Thiyl Radical ◽  
Methyl Ethyl ◽  
Disulfide Linkage ◽  
Thiyl Radicals ◽  
Disulfide Formation ◽  
Photostationary State ◽  
State Concentration

The photolysis of mixtures of liquid methyl disulfide and ethyl disulfide at room temperature at wavelengths greater than 2300 Å has been investigated. The sole detectable product is methyl ethyl disulfide which reaches a photostationary state concentration after relatively short irradiation periods. For various initial mixtures, the concentration of the three disulfides in the photostationary state can be correlated in terms of an equilibrium constant, K = [RSSR′]/[RSSR]1/2[R′SSR′]1/2, whose value is 2.05 ± 0.04. The quantum yield of unsymmetrical disulfide formation in the initial stages of the reaction is 330 for an absorbed intensity of 4.70 × 10−2 μeinstein/min when the incident radiation is confined to λ = 2600 + 50 Å. The exceptionally high efficiency of the overall process is ascribed to the chain-propagating step[Formula: see text]which likely proceeds through attack of the thiyl radical on the S—S disulfide linkage.

Reactions of thiyl radicals. V. The gas phase photolysis of methyl disulfide and ethyl disulfide mixtures in the presence of ethylene

1968 ◽  
Vol 46 (14) ◽  
pp. 2462-2464 ◽  
Author(s):  
P. M. Rao ◽  
A. R. Knight
Keyword(s):  
Gas Phase ◽  
Methyl Ethyl ◽  
Thiyl Radicals ◽  
Disulfide Formation ◽  
Presence And Absence ◽  
Low Efficiency

The gas phase photolysis of methyl disulfide and ethyl disulfide and their mixtures, in the presence and absence of ethylene, has been studied at 25 °C and λ = 2300–2800 Å. The pure substrates give predominantly the corresponding thiol, whereas co-photolysis yields methyl ethyl disulfide in appreciably larger yields.When ethylene is added, the substrates individually show a reduction in RSH rate and the formation of relatively small amounts of sulfides. In their co-photolysis, added C2H4 does not appreciably alter the rate of methyl ethyl disulfide formation, indicating a low efficiency of RS scavenging by the olefin in this system.Isopropanol and 2,3-dimethyl butane do not increase the thiol yield from the pure substrates.

Clustering-Triggered Efficient Room Temperature Phosphorescence from Nonconventional Luminophores

2019 ◽  
Author(s):  
Shuyuan Zheng ◽  
Taiping Hu ◽  
Xin Bin ◽  
Yunzhong Wang ◽  
Yuanping Yi ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Spin Orbit Coupling ◽  
Design Rationale ◽  
Emission Mechanism ◽  
Room Temperature Phosphorescence ◽  
Electronic Interactions ◽  
Energy Gaps ◽  
Theoretical Results

Pure organic room temperature phosphorescence (RTP) and luminescence from nonconventional luminophores have gained increasing attention. However, it remains challenging to achieve efficient RTP from unorthodox luminophores, on account of the unsophisticated understanding of the emission mechanism. Here we propose a strategy to realize efficient RTP in nonconventional luminophores through incorporation of lone pairs together with clustering and effective electronic interactions. The former promotes spin-orbit coupling and boost the consequent intersystem crossing, whereas the latter narrows energy gaps and stabilizes the triplets, thus synergistically affording remarkable RTP. Experimental and theoretical results of urea and its derivatives verify the design rationale. Remarkably, RTP from thiourea solids with unprecedentedly high efficiency of up to 24.5% is obtained. Further control experiments testify the crucial role of through-space delocalization on the emission. These results would spur the future fabrication of nonconventional phosphors, and moreover should advance understanding of the underlying emission mechanism.<br>

Fast, high-efficiency, and homogeneous room-temperature cathodoluminescence of ZnO scintillator thin films on sapphire

2006 ◽  
Vol 89 (24) ◽  
pp. 243510 ◽  
Author(s):  
M. Lorenz ◽  
R. Johne ◽  
T. Nobis ◽  
H. Hochmuth ◽  
J. Lenzner ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
High Efficiency

Barium calcium titanate @carbon hybrid materials for high-efficiency room-temperature pyrocatalysis

2021 ◽  
Author(s):  
Huiying Wang ◽  
Yanmin Jia ◽  
Taosheng Xu ◽  
Xiaoxin Shu ◽  
Yiming He ◽  
...  
Keyword(s):  
Hybrid Materials ◽  
Room Temperature ◽  
High Efficiency ◽  
Calcium Titanate

scholarly journals Measurement of Ozone Production Sensor

2010 ◽  
Vol 3 (3) ◽  
pp. 545-555 ◽  
Author(s):  
M. Cazorla ◽  
W. H. Brune
Keyword(s):  
Production Rate ◽  
High Efficiency ◽  
Ambient Air ◽  
Ozone Production ◽  
State University ◽  
Photostationary State ◽  
Sample Chamber ◽  
Efficiency Conversion ◽  
The Difference ◽  
Teflon Film

Abstract. A new ambient air monitor, the Measurement of Ozone Production Sensor (MOPS), measures directly the rate of ozone production in the atmosphere. The sensor consists of two 11.3 L environmental chambers made of UV-transmitting Teflon film, a unit to convert NO2 to O3, and a modified ozone monitor. In the sample chamber, flowing ambient air is exposed to the sunlight so that ozone is produced just as it is in the atmosphere. In the second chamber, called the reference chamber, a UV-blocking film over the Teflon film prevents ozone formation but allows other processes to occur as they do in the sample chamber. The air flows that exit the two chambers are sampled by an ozone monitor operating in differential mode so that the difference between the two ozone signals, divided by the exposure time in the chambers, gives the ozone production rate. High-efficiency conversion of NO2 to O3 prior to detection in the ozone monitor accounts for differences in the NOx photostationary state that can occur in the two chambers. The MOPS measures the ozone production rate, but with the addition of NO to the sampled air flow, the MOPS can be used to study the sensitivity of ozone production to NO. Preliminary studies with the MOPS on the campus of the Pennsylvania State University show the potential of this new technique.

Reactions of Thiyl Radicals. XI. Further Investigations of Thiol–Disulfide Photolyses in the Liquid Phase

1973 ◽  
Vol 51 (9) ◽  
pp. 1410-1415 ◽  
Author(s):  
Donna D. Carlson ◽  
Arthur R. Knight
Keyword(s):  
Liquid Phase ◽  
Room Temperature ◽  
Liquid Mixtures ◽  
Quantum Yields ◽  
Chain Reaction ◽  
Photochemical Process ◽  
High Quantum Efficiency ◽  
Thiyl Radicals ◽  
Exchange Processes ◽  
A Chain

The photolysis of C2H5SH liquid at 2537 Å has been shown to give H2 and C2H5SSC2H5 at equal rates with a quantum yield of 0.25. The photolysis of ethanethiol – methyl disulfide liquid mixtures leads, via a chain reaction involving propagation by attack of thiyl radicals on the disulfide S—S bond, to the formation with high quantum efficiency of CH3SH, C2H5SSC2H5 and, as an intermediate that is consumed after long exposures, CH3SSC2H5. The net result of the sequence of exchange processes is the essentially irreversible conversion of the methyl disulfide into methanethiol. The same overall reaction occurs thermally at room temperature, but the rate is appreciably less than that of the photochemical process. The quantum yields of formation of the unsymmetrical disulfides arising from the photochemically initiated exchange reaction in equimolar mixtures of CH3SSCH3 + n-C3H7SSC3H7 and C2H5SSC2H5 + n-C3H7SSC3H7 have been shown to be 6.9 and 4.4, compared to 355 for CH3-SSCH3 + C2H5SSC2H5 mixtures. In all three types of system examined in this investigation all thiyl radicals can be accounted for stoichiometrically on the basis of exchange and combination reactions alone, indicating negligible disproportionation of these species in condensed phase.

A mild heteroatom (O-, N-, and S-) methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2 combination

Synthesis ◽  
2022 ◽  
Author(s):  
Yu Tang ◽  
Biao Yu
Keyword(s):  
Cost Efficiency ◽  
Room Temperature ◽  
High Efficiency ◽  
Attractive Alternative ◽  
Indole Derivatives ◽  
Trimethyl Phosphate ◽  
Environmental Friendly ◽  
Operational Simplicity

A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2 combination has been developed, which proceeds in DMF, or water, or under neat conditions at 80 oC or at room temperature. A series of O-, N- and S-nucleophiles, including phenols, sulfonamides, N-heterocycles such as 9H-carbazole, indole derivatives, 1,8-naphthalimide, and aryl/alkyl thiols are suitable substrates of this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmental friendly nature of this protocol make it an attractive alternative to the conventional base prompted heteroatom methylation procedures.

Modulating room temperature spin injection into GaN towards the high-efficiency spin-light emitting diodes

2020 ◽  
Vol 13 (4) ◽  
pp. 043006 ◽  
Author(s):  
Anke Song ◽  
Jiajun Chen ◽  
Jinshen Lan ◽  
Deyi Fu ◽  
Jiangpeng Zhou ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Spin Injection ◽  
Light Emitting
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