Linked Life Data

17867659

Source:http://linkedlifedata.com/resource/pubmed/id/17867659

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2007-10-4
pubmed:abstractText
The ultrafast photofragmentation of arylperoxycarbonates R-O-C(O)O-O-tert-butyl (R = naphthyl, phenyl) is studied using femtosecond UV excitation at 266 nm and mid-infrared broadband probe pulses to elucidate the dissociation mechanism. Our experiments show that the rate of fragmentation is determined by the S1-lifetime of the peroxide, i.e., the time constants of S1 decay and of CO2 and R-O* formation are identical. The fragmentation times are solvent dependent and for tert-butyl-2-naphthylperoxycarbonate (TBNC) vary from 25 ps in CH2Cl2 to 52 ps in n-heptane. In the case of the tert-butylphenylperoxycarbonate (TBPC) the decomposition takes 5.5 ps in CD2Cl2 and 12 ps in n-heptane. The CO2 fragment is formed vibrationally hot with an excess energy of about 5000 cm(-1). The hot CO2 spectra at high energy can be modeled assuming Boltzmann distributions with initial vibrational temperatures of ca. 2500 K which relax to ambient temperature with time constants of 280 ps in CCl4 and 130 ps in n-heptane. In CCl4 the relaxed spectra at 1.5 ns show 3.5% residual excitation in the n = 1 level of the asymmetric stretch vibration.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
1089-5639
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
111
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10111-8
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Femtosecond IR spectroscopy of peroxycarbonate photodecomposition: S1-lifetime determines decarboxylation rate.
pubmed:affiliation
Abteilung Spektroskopie und Photochemische Kinetik, Max-Planck-Institut für Biophysikalische Chemie, 37070 Göttingen, Germany.
pubmed:publicationType
Journal Article