Kinetic analysis of the photochemistry of alkyldiazenes in hydrocarbon solution. The quasi-steady state

Anne Mee Thompson, P. C. Goswami, G. L. Zimmerman

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

A kinetic method, analogous to those which describe completely reversible photochemical transformations, has been developed for measuring quantum yields in systems characterized by simultaneous reversible and irreversible photochemical reactions. Based on the concept of a "quasi-steady state", in which there is no net reversible reaction but a constant-composition mixture undergoing an irreversible reaction, it facilitates calculation of both reversible and irreversible quantum yields from the kinetics of a single irradiation of the interconverting specieis. The analysis has been applied to irradiation in the n,π* band of azomethane, azoisopropane, and phenylazomethane in benzene or isooctane; for the first two systems free-radical decomposition competes with reversible cis-trans isomerization, whereas for phenylazomethane only reversible isomerization occurs. For the 365-nm irradiation of azomethane (the more interesting case) the following quantum yields are found: φtrans→cis = 0.42 ± 0.01, φcis→trans = 0.45 ± 0.01, φtrans→dec = 0.089 ± 0.01, φcis→dec = 0.008 ± 0.01. These results are consistent with data from numerous other investigations of azomethane and lend support to a mechanistic interpretation of alkyldiazene photochemistry in which decomposition occurs from the unrelaxed S1 state of each isomer and isomerization takes place from an intermediate form of T1.

Original languageEnglish (US)
Pages (from-to)314-320
Number of pages7
JournalJournal of Physical Chemistry
Volume83
Issue number3
DOIs
StatePublished - Jan 1 1979

Fingerprint

quasi-steady states
Photochemical reactions
Quantum yield
Isomerization
Hydrocarbons
photochemical reactions
isomerization
hydrocarbons
Irradiation
Kinetics
irradiation
kinetics
Decomposition
decomposition
Benzene
Free radicals
Isomers
free radicals
Free Radicals
isomers

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physical and Theoretical Chemistry

Cite this

Thompson, Anne Mee ; Goswami, P. C. ; Zimmerman, G. L. / Kinetic analysis of the photochemistry of alkyldiazenes in hydrocarbon solution. The quasi-steady state. In: Journal of Physical Chemistry. 1979 ; Vol. 83, No. 3. pp. 314-320.
@article{fceb35f023e54d3d817521a60dcba625,
title = "Kinetic analysis of the photochemistry of alkyldiazenes in hydrocarbon solution. The quasi-steady state",
abstract = "A kinetic method, analogous to those which describe completely reversible photochemical transformations, has been developed for measuring quantum yields in systems characterized by simultaneous reversible and irreversible photochemical reactions. Based on the concept of a {"}quasi-steady state{"}, in which there is no net reversible reaction but a constant-composition mixture undergoing an irreversible reaction, it facilitates calculation of both reversible and irreversible quantum yields from the kinetics of a single irradiation of the interconverting specieis. The analysis has been applied to irradiation in the n,π* band of azomethane, azoisopropane, and phenylazomethane in benzene or isooctane; for the first two systems free-radical decomposition competes with reversible cis-trans isomerization, whereas for phenylazomethane only reversible isomerization occurs. For the 365-nm irradiation of azomethane (the more interesting case) the following quantum yields are found: φtrans→cis = 0.42 ± 0.01, φcis→trans = 0.45 ± 0.01, φtrans→dec = 0.089 ± 0.01, φcis→dec = 0.008 ± 0.01. These results are consistent with data from numerous other investigations of azomethane and lend support to a mechanistic interpretation of alkyldiazene photochemistry in which decomposition occurs from the unrelaxed S1 state of each isomer and isomerization takes place from an intermediate form of T1.",
author = "Thompson, {Anne Mee} and Goswami, {P. C.} and Zimmerman, {G. L.}",
year = "1979",
month = "1",
day = "1",
doi = "10.1021/j100466a003",
language = "English (US)",
volume = "83",
pages = "314--320",
journal = "Journal of Physical Chemistry",
issn = "0022-3654",
publisher = "American Chemical Society",
number = "3",

}

Kinetic analysis of the photochemistry of alkyldiazenes in hydrocarbon solution. The quasi-steady state. / Thompson, Anne Mee; Goswami, P. C.; Zimmerman, G. L.

In: Journal of Physical Chemistry, Vol. 83, No. 3, 01.01.1979, p. 314-320.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Kinetic analysis of the photochemistry of alkyldiazenes in hydrocarbon solution. The quasi-steady state

AU - Thompson, Anne Mee

AU - Goswami, P. C.

AU - Zimmerman, G. L.

PY - 1979/1/1

Y1 - 1979/1/1

N2 - A kinetic method, analogous to those which describe completely reversible photochemical transformations, has been developed for measuring quantum yields in systems characterized by simultaneous reversible and irreversible photochemical reactions. Based on the concept of a "quasi-steady state", in which there is no net reversible reaction but a constant-composition mixture undergoing an irreversible reaction, it facilitates calculation of both reversible and irreversible quantum yields from the kinetics of a single irradiation of the interconverting specieis. The analysis has been applied to irradiation in the n,π* band of azomethane, azoisopropane, and phenylazomethane in benzene or isooctane; for the first two systems free-radical decomposition competes with reversible cis-trans isomerization, whereas for phenylazomethane only reversible isomerization occurs. For the 365-nm irradiation of azomethane (the more interesting case) the following quantum yields are found: φtrans→cis = 0.42 ± 0.01, φcis→trans = 0.45 ± 0.01, φtrans→dec = 0.089 ± 0.01, φcis→dec = 0.008 ± 0.01. These results are consistent with data from numerous other investigations of azomethane and lend support to a mechanistic interpretation of alkyldiazene photochemistry in which decomposition occurs from the unrelaxed S1 state of each isomer and isomerization takes place from an intermediate form of T1.

AB - A kinetic method, analogous to those which describe completely reversible photochemical transformations, has been developed for measuring quantum yields in systems characterized by simultaneous reversible and irreversible photochemical reactions. Based on the concept of a "quasi-steady state", in which there is no net reversible reaction but a constant-composition mixture undergoing an irreversible reaction, it facilitates calculation of both reversible and irreversible quantum yields from the kinetics of a single irradiation of the interconverting specieis. The analysis has been applied to irradiation in the n,π* band of azomethane, azoisopropane, and phenylazomethane in benzene or isooctane; for the first two systems free-radical decomposition competes with reversible cis-trans isomerization, whereas for phenylazomethane only reversible isomerization occurs. For the 365-nm irradiation of azomethane (the more interesting case) the following quantum yields are found: φtrans→cis = 0.42 ± 0.01, φcis→trans = 0.45 ± 0.01, φtrans→dec = 0.089 ± 0.01, φcis→dec = 0.008 ± 0.01. These results are consistent with data from numerous other investigations of azomethane and lend support to a mechanistic interpretation of alkyldiazene photochemistry in which decomposition occurs from the unrelaxed S1 state of each isomer and isomerization takes place from an intermediate form of T1.

UR - http://www.scopus.com/inward/record.url?scp=0003425025&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0003425025&partnerID=8YFLogxK

U2 - 10.1021/j100466a003

DO - 10.1021/j100466a003

M3 - Article

VL - 83

SP - 314

EP - 320

JO - Journal of Physical Chemistry

JF - Journal of Physical Chemistry

SN - 0022-3654

IS - 3

ER -