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Pregled bibliografske jedinice broj: 265083

Luminescence and Raman spectra of acetylacetone at low temperatures


Mohaček Grošev, Vlasta; Furić, Krešimir; Ivanković, Hrvoje
Luminescence and Raman spectra of acetylacetone at low temperatures // The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 111 (2007), 26; 5820-5827 doi:10.1021/jp067157j (međunarodna recenzija, članak, znanstveni)


Naslov
Luminescence and Raman spectra of acetylacetone at low temperatures

Autori
Mohaček Grošev, Vlasta ; Furić, Krešimir ; Ivanković, Hrvoje

Izvornik
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory (1089-5639) 111 (2007), 26; 5820-5827

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Fluorescence ; singlet-triplet mixing ; methyl group ; enol-keto tautomerism ; isomers

Sažetak
Raman spectra of acetylacetone were recorded for molecules isolated in an argon matrix at 10 K and for polycrystalline sample. In solid sample broad bands appear superimposed on much weaker Raman spectrum corresponding to the stable Cs enol. Their position depends on the excitation wavelength (514.5 nm and 488.8 argon ion laser lines were used), sample temperature and cooling history. These bands are attributed to transitions from excited higher electronic state to various isomer states in the ground electronic state. Laser photons excite acetylacetone in crystal in the region where a number of excited triplet states are predicted for a free acetylacetone molecule (X.B. Chen et al. J. Phys. Chem. A 110 (2006) 4434.). Since singlet to triplet photon absorption transitions are forbidden, states existing in solid have mixed singlet/triplet character. Their decay results in population of different isomer states which are not vibrationally resolved except for the lowest isomers: Cs enol, C2v enol (here denoting possibly both TS1 and TS2 transition states described in Matanović and Došlić, J. Phys. Chem. A 109 (2005) 4185.), and keto form which can be detected in solid Raman spectra. Differential scanning calorimetry showed two signals on cooling of acetylacetone, one at 229 K and one at 217 K, while on heating they appear at 254 K and 225 K. The phase change at higher temperature is attributed to freezing/melting transition, while the one at lower temperature seems to correspond to freezing/melting of keto domains as suggested by Johnson et al. [ J. Chem. Phys. 116 (2002) 5694]. Using matrix isolation in argon technique, vibrational spectrum of acetylacetone at 10 K was recorded. Two bands at 3113 cm-1 and 3083 cm-1 are assigned to methyne CH stretching vibration of Cs and C2v enol conformers. Strong bands at 1602 cm-1 and 1629 cm-1 are assigned as Cs enol bands, and weaker underlying band at 1687 cm-1 and medium band at 1617 cm-1 as C2v enol bands.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemijsko inženjerstvo



POVEZANOST RADA


Projekt / tema
0098019
0098022
0125019

Ustanove
Institut "Ruđer Bošković", Zagreb,
Fakultet kemijskog inženjerstva i tehnologije, Zagreb

Časopis indeksira:


  • Current Contents Connect (CCC)
  • Web of Science Core Collection (WoSCC)
    • Science Citation Index Expanded (SCI-EXP)
    • SCI-EXP, SSCI i/ili A&HCI
  • Scopus
  • MEDLINE


Uključenost u ostale bibliografske baze podataka:


  • Chemical Abstracts


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