photostationary state

2020 ◽  
Author(s):  
N. Brosy
Keyword(s):  
Photostationary State

Photochemical cis-trans Isomerization of 2-Substituted 9-(2-Nitroethenyl)anthracenes. X-Ray Structure Analyses of (E)- and (Z)-9-(2-Nitro-2-phenylethenyl)anthracene

1989 ◽  
Vol 42 (4) ◽  
pp. 593 ◽  
Author(s):  
HD Becker ◽  
BW Skelton ◽  
H Sorensen ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Quantum Yields ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photostationary State ◽  
Trans Isomerization ◽  
Photochemical Isomerization

(E)-9-(2-Nitropropeny1)anthracene and (E)-9-(2-nitro-2-phenylethenyl)anthracene have been prepared by piperidine-catalysed condensation of 9-anthraldehyde with nitroethane and nitro(phenyl)methane, respectively. The corresponding (Z)-compounds were obtained by photochemical isomerization, quantum yields of geometrical isomerlzation being measured in cyclohexane, benzene, dichloromethane and ethanol. In virtually all solvents the (Z)-isomers are favoured at the photostationary state. The structures of (E)- and (2)-942- nitro-2-phenylethenyl)anthracene have been established by single-crystal X-ray diffraction studies.

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.

On the photostationary state of the flavylium network of chemical reactions

2013 ◽  
Vol 269 ◽  
pp. 1-8 ◽  
Author(s):  
Fernando Pina ◽  
Raquel Gomes ◽  
Nuno Basílio ◽  
César A.T. Laia
Keyword(s):  
Chemical Reactions ◽  
Photostationary State

Metal-binding hydrazone photoswitches for visible light reactivity and variable relaxation kinetics

2017 ◽  
Vol 16 (11) ◽  
pp. 1604-1612 ◽  
Author(s):  
Kacey C. Hall ◽  
Andrew T. Franks ◽  
Rory C. McAtee ◽  
Michael S. Wang ◽  
Vivian I. Lu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Visible Light ◽  
Binding Affinity ◽  
Blue Light ◽  
Metal Binding ◽  
Relaxation Kinetics ◽  
Photostationary State ◽  
State Composition

Photoactive aroylhydrazones demonstrate variability in UVA, UVC and blue light photoreactivity, photostationary state composition, photoisomer thermal stability, and relative iron(iii) binding affinity in ways that may inform metal-gated photoswitching applications.

Synthesis and properties of macrocyclic diazene switch with binaphthalene unit attached via acrylamide linkers

2013 ◽  
Vol 67 (1) ◽  
Author(s):  
Anna Kicková ◽  
Branislav Horváth ◽  
Lukáš Kerner ◽  
Martin Putala
Keyword(s):  
Methyl Acrylate ◽  
Heck Reaction ◽  
Knoevenagel Condensation ◽  
Equimolar Mixture ◽  
Cd Spectra ◽  
Photostationary State ◽  
End Groups

Abstract2,2′-Diiodo-1,1′-binaphthalene undergoes a tandem Heck reaction with methyl acrylate to afford methyl 2-(7H-dibenzo[c,g]fluoren-7-ylidene)acetate. As a consequence, the target macrocyclic diazene with binaphthalene unit attached via acrylamide linker was prepared by the stepwise building of acrylamide at a binaphthalene moiety, including the Doebner modification of the Knoevenagel condensation, and completed by oxidative macrocyclisation of aniline end-groups. Despite being an equimolar mixture of monomer and dimer, it exhibited remarkable changes in CD spectra due to reversible (E/Z) isomerisation of N=N diazene bonds upon irradiation at 365/465 nm. Although the dimer isomerises from (E) to (Z) isomer 7.4 times faster than the monomer, the latter’s contribution to the change in ellipticity at 307 nm in the photostationary state is 2.4 times greater.

Synthesis and Properties of 1-[2-trifluoromethylpheny-2-[2-methyl-5-(3,5-difluorophenyl)-3-thienyl] perfluorocyclopentene

2013 ◽  
Vol 468 ◽  
pp. 75-78
Author(s):  
Guang Ming Liao ◽  
Shou Zhi Pu ◽  
Zhi Yuan Sun
Keyword(s):  
Absorption Band ◽  
Fluorescence Intensity ◽  
Emission Intensity ◽  
Uv Light ◽  
Fluorescent Properties ◽  
Visible Absorption ◽  
Photostationary State ◽  
Closed Ring ◽  
Open Ring

An asymmetrical photochromic diarylethene 1-[2-trifluoromethylpheny-2-[2-methyl-5-(3,5-difluorophenyl)-3-thienyperfluorocyclopentene (1o) was synthesized and its phtochromic, fluorescent properties in both solution and PMMA films were investigated in detail. This compound exhibited remarkable photochromism, upon irradiation with 297 nm UV light, the colorless solution of 1o turned to plum with a new visible absorption band centered at 544 nm (ε =3.75 × 103 L mol-1 cm-1) attributable to the closed-ring isomer 1c.The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer in PMMA films and in hexane. The emission intensity of diarylethene 1o in a photostationary state was quenched to ca. 64% in hexane and 27% in PMMA films.

scholarly journals A comparison of HONO budgets for two measurement heights at a field station within the boreal forest in Finland

2015 ◽  
Vol 15 (2) ◽  
pp. 799-813 ◽  
Author(s):  
R. Oswald ◽  
M. Ermel ◽  
K. Hens ◽  
A. Novelli ◽  
H. G. Ouwersloot ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Gas Phase Reactions ◽  
Additional Source ◽  
Forest Environment ◽  
Field Station ◽  
Photostationary State ◽  
Unknown Source ◽  
Unidentified Source ◽  
Photolytic Decomposition ◽  
Atmospheric Concentrations

Abstract. Atmospheric concentrations of nitrous acid (HONO), one of the major precursors of the hydroxyl radical (OH) in the troposphere, significantly exceed the values predicted by the assumption of a photostationary state (PSS) during daytime. Therefore, additional sources of HONO were intensively investigated in the last decades. This study presents budget calculations of HONO based on simultaneous measurements of all relevant species, including HONO and OH at two different measurement heights, i.e. 1 m above the ground and about 2 to 3 m above the canopy (24 m above the ground), conducted in a boreal forest environment. We observed mean HONO concentrations of about 6.5 × 108 molecules cm−3 (26 ppt) during daytime, more than 20 times higher than expected from the PSS of 0.2 × 108 molecules cm−3 (1 ppt). To close the budgets at both heights, a strong additional source term during daytime is required. This unidentified source is at its maximum at noon (up to 1.1 × 106 molecules cm−3 s−1, 160 ppt h−1) and in general up to 2.3 times stronger above the canopy than close to the ground. The insignificance of known gas phase reactions and other processes like dry deposition or advection compared to the photolytic decomposition of HONO at this measurement site was an ideal prerequisite to study possible correlations of this unknown term to proposed HONO sources. But neither the proposed emissions from soils nor the proposed photolysis of adsorbed HNO3 contributed substantially to the unknown source. However, the unknown source was found to be perfectly correlated to the unbalanced photolytic loss of HONO.

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