Intramolecular charge transfer excitation induced by CH3O substitution in 3-methoxy-1-propoxy radical

2021 ◽  
Author(s):  
Junfei Xue ◽  
Tai Qin ◽  
Lily Zu
Keyword(s):  
Charge Transfer ◽  
Secondary Organic Aerosol ◽  
Intramolecular Charge Transfer ◽  
Organic Aerosol ◽  
Ozone Production ◽  
Alkoxy Radicals ◽  
Charge Transfer Excitation

The oxy-substituted alkoxy radicals are generated in the oxidation of ethers. Its degradation path affects the ozone production and the formation of secondary organic aerosol in atmosphere. In this work,...

scholarly journals Investigation of the correlation between odd oxygen and secondary organic aerosol in Mexico City and Houston

2010 ◽  
Vol 10 (2) ◽  
pp. 3547-3604 ◽  
Author(s):  
E. C. Wood ◽  
M. R. Canagaratna ◽  
S. C. Herndon ◽  
J. H. Kroll ◽  
T. B. Onasch ◽  
...  
Keyword(s):  
Mexico City ◽  
Secondary Organic Aerosol ◽  
Formation Rate ◽  
Organic Aerosol ◽  
Ozone Production ◽  
Volatile Components ◽  
Petrochemical Plant ◽  
Plant Emissions ◽  
Photochemical Aging ◽  
Odd Oxygen

Abstract. Many recent models underpredict secondary organic aerosol (SOA) particulate matter (PM) concentrations in polluted regions, indicating serious deficiencies in the models' chemical mechanisms and/or missing SOA precursors. Since tropospheric photochemical ozone production is much better understood, we investigate the correlation of odd-oxygen ([Ox]≡[O3]+[NO2]) and the oxygenated component of organic aerosol (OOA), which is interpreted as a surrogate for SOA. OOA and Ox measured in Mexico City in 2006 and Houston in 2000 were well correlated in air masses where both species were formed on similar timescales (less than 8 h) and not well correlated when their formation timescales or location differed greatly. When correlated, the ratio of these two species ranged from 30 μg m−3 ppm−1 (STP) in Houston during time periods affected by large petrochemical plant emissions to as high as 160 μg m−3 ppm−1 in Mexico City, where typical values were near 120 μg m−3 ppm−1. On several days in Mexico City, the [OOA]/[Ox] ratio decreased by a factor of ~2 between 08:00 and 13:00 LT. This decrease is only partially attributable to evaporation of the least oxidized and most volatile components of OOA; differences in the diurnal emission trends and timescales for photochemical processing of SOA precursors compared to ozone precursors also likely contribute to the observed decrease. The extent of OOA oxidation increased with photochemical aging. Calculations of the ratio of the SOA formation rate to the Ox production rate using ambient VOC measurements and traditional laboratory SOA yields are lower than the observed [OOA]/[Ox] ratios by factors of 5 to 15, consistent with several other models' underestimates of SOA. Calculations of this ratio using emission factors for organic compounds from gasoline and diesel exhaust do not reproduce the observed ratio. Although not succesful in reproducing the atmospheric observations presented, modeling P(SOA)/P(Ox) can serve as a useful test of photochemical models using improved formulation mechanisms for SOA.

scholarly journals Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

2007 ◽  
Vol 7 (19) ◽  
pp. 5159-5174 ◽  
Author(s):  
N. L. Ng ◽  
P. S. Chhabra ◽  
A. W. H. Chan ◽  
J. D. Surratt ◽  
J. H. Kroll ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Organic Nitrates ◽  
Biogenic Hydrocarbons ◽  
Alkoxy Radicals ◽  
Volatile Products ◽  
Products Analysis ◽  
Environmental Chambers ◽  
Aerosol Chemical Composition

Abstract. Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (longifolene and aromadendrene) is investigated in the Caltech environmental chambers. The effect of NOx on SOA formation for these biogenic hydrocarbons is evaluated by performing photooxidation experiments under varying NOx conditions. The NOx dependence of α-pinene SOA formation follows the same trend as that observed previously for a number of SOA precursors, including isoprene, in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NOx level increases. The NOx dependence of SOA yield for the sesquiterpenes, longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NOx conditions substantially exceeds that under low-NOx conditions. The reversal of the NOx dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively low-volatility organic nitrates, and/or the isomerization of large alkoxy radicals leading to less volatile products. Analysis of the aerosol chemical composition for longifolene confirms the presence of organic nitrates under high-NOx conditions. Consequently the formation of SOA from certain biogenic hydrocarbons such as sesquiterpenes (and possibly large anthropogenic hydrocarbons as well) may be more efficient in polluted air.

scholarly journals Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

2007 ◽  
Vol 7 (4) ◽  
pp. 10131-10177 ◽  
Author(s):  
N. L. Ng ◽  
P. S. Chhabra ◽  
A. W. H. Chan ◽  
J. D. Surratt ◽  
J. H. Kroll ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Organic Nitrates ◽  
Biogenic Hydrocarbons ◽  
Alkoxy Radicals ◽  
Volatile Products ◽  
Products Analysis ◽  
Environmental Chambers ◽  
Aerosol Chemical Composition

Abstract. Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (longifolene and aromadendrene) is investigated in the Caltech environmental chambers. The effect of NOx on SOA formation for these biogenic hydrocarbons is evaluated by performing photooxidation experiments under varying NOx conditions. The NOx dependence of α-pinene SOA formation follows the same trend as that observed previously for a number of SOA precursors, including isoprene, in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NOx level increases. The NOx dependence of SOA yield for the sesquiterpenes, longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NOx conditions substantially exceeds that under low-NOx conditions. The reversal of the NOx dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively low-volatility organic nitrates, and/or the isomerization of large alkoxy radicals leading to less volatile products. Analysis of the aerosol chemical composition for longifolene confirms the presence of organic nitrates under high-NOx conditions. Consequently the formation of SOA from certain biogenic hydrocarbons such as sesquiterpenes (and possibly large anthropogenic hydrocarbons as well) may be more efficient in polluted air.

Failures of TDDFT in describing the lowest intramolecular charge-transfer excitation in para-nitroaniline

2013 ◽  
Vol 111 (9-11) ◽  
pp. 1235-1248 ◽  
Author(s):  
Janus J. Eriksen ◽  
Stephan P.A. Sauer ◽  
Kurt V. Mikkelsen ◽  
Ove Christiansen ◽  
Hans Jørgen Aa. Jensen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Charge Transfer Excitation

scholarly journals Investigation of the correlation between odd oxygen and secondary organic aerosol in Mexico City and Houston

2010 ◽  
Vol 10 (18) ◽  
pp. 8947-8968 ◽  
Author(s):  
E. C. Wood ◽  
M. R. Canagaratna ◽  
S. C. Herndon ◽  
T. B. Onasch ◽  
C. E. Kolb ◽  
...  
Keyword(s):  
Mexico City ◽  
Secondary Organic Aerosol ◽  
Formation Rate ◽  
Organic Aerosol ◽  
Ozone Production ◽  
Volatile Components ◽  
Petrochemical Plant ◽  
Plant Emissions ◽  
Photochemical Aging ◽  
Odd Oxygen

Abstract. Many recent models underpredict secondary organic aerosol (SOA) particulate matter (PM) concentrations in polluted regions, indicating serious deficiencies in the models' chemical mechanisms and/or missing SOA precursors. Since tropospheric photochemical ozone production is much better understood, we investigate the correlation of odd-oxygen ([Ox]≡[O3]+[NO2]) and the oxygenated component of organic aerosol (OOA), which is interpreted as a surrogate for SOA. OOA and Ox measured in Mexico City in 2006 and Houston in 2000 were well correlated in air masses where both species were formed on similar timescales (less than 8 h) and not well correlated when their formation timescales or location differed greatly. When correlated, the ratio of these two species ranged from 30 μg m−3/ppm (STP) in Houston during time periods affected by large petrochemical plant emissions to as high as 160 μg m−3/ppm in Mexico City, where typical values were near 120 μg m−3/ppm. On several days in Mexico City, the [OOA]/[Ox] ratio decreased by a factor of ~2 between 08:00 and 13:00 local time. This decrease is only partially attributable to evaporation of the least oxidized and most volatile components of OOA; differences in the diurnal emission trends and timescales for photochemical processing of SOA precursors compared to ozone precursors also likely contribute to the observed decrease. The extent of OOA oxidation increased with photochemical aging. Calculations of the ratio of the SOA formation rate to the Ox production rate using ambient VOC measurements and traditional laboratory SOA yields are lower than the observed [OOA]/[Ox] ratios by factors of 5 to 15, consistent with several other models' underestimates of SOA. Calculations of this ratio using emission factors for organic compounds from gasoline and diesel exhaust do not reproduce the observed ratio. Although not succesful in reproducing the atmospheric observations presented, modeling P(SOA)/P(Ox) can serve as a useful test of photochemical models using improved formulation mechanisms for SOA.

Dynamic adjustment of emission from both singlets and triplets: the role of excited state conformation relaxation and charge transfer in phenothiazine derivates

2021 ◽  
Author(s):  
Weidong Qiu ◽  
Xinyi Cai ◽  
Mengke Li ◽  
Liangying Wang ◽  
Yanmei He ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Dynamic Adjustment ◽  
Twisted Intramolecular Charge Transfer

Dynamic adjustment of emission behaviours by controlling the extent of twisted intramolecular charge transfer character in excited state.

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