The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds
<p>The excited state structural relaxation of <mml:math alttext="$4$"> <mml:mn>4</mml:mn> </mml:math>-dimethylaminobenzenes with various <emph>para</emph>-acceptor substituents having double-band emission, local excited (LE) and charge transfer (...
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| Language: | English |
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Wiley
2006-01-01
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| Series: | International Journal of Photoenergy |
| Online Access: | http://www.hindawi.com/GetArticle.aspx?doi=10.1155/IJP/2006/81896 |
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| description | <p>The excited state structural relaxation of <mml:math alttext="$4$"> <mml:mn>4</mml:mn> </mml:math>-dimethylaminobenzenes with various <emph>para</emph>-acceptor substituents having double-band emission, local excited (LE) and charge transfer (CT), has been investigated. Fluorescence measurements at different temperatures and in different solvents have confirmed the existence of viscosity-dependent, temperature, and polarity-activated relaxation. The kinetics analysis has shown that the radiative deactivation rate constants of the individual LE and CT states differ by <mml:math alttext="$7$"> <mml:mn>7</mml:mn> </mml:math>–<mml:math alttext="$112$"> <mml:mn>112</mml:mn> </mml:math>-fold. The dipole moment changes at the excitation for CT states are significantly larger than those for LE states. The spectral-kinetics behavior of compounds studied agrees with the models <mml:math alttext="$ext{A} ightarrowext{A}^ast ightarrowext{B}^ast$"> <mml:mrow> <mml:mtext>A</mml:mtext><mml:mo>→</mml:mo><mml:msup> <mml:mtext>A</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> <mml:mo>→</mml:mo><mml:msup> <mml:mtext>B</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:mrow> </mml:math> or <mml:math alttext="$ext{A} ightarrowext{A}^astleftrightarrowext{B}^ast$"> <mml:mtext>A</mml:mtext><mml:mo>→</mml:mo><mml:msup> <mml:mtext>A</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> <mml:mo>↔</mml:mo><mml:msup> <mml:mtext>B</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:math>, where <mml:math alttext="$ext{A}^{ast}$"> <mml:msup> <mml:mtext>A</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:math> is the local excited planar and <mml:math alttext="$ext{B}^{ast}$"> <mml:msup> <mml:mtext>B</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:math> is the relaxed twisted state of the molecule. The rate constants of the twisted state formation have been calculated in the temperature range <mml:math alttext="$293$"> <mml:mn>293</mml:mn> </mml:math>–<mml:math alttext="$77$"> <mml:mn>77</mml:mn> </mml:math> K. The activation energies of forward process for compounds studied have been estimated.</p> |
| format | Article |
| id | doaj-art-5741909781b04008a7f6964ab6052a08 |
| institution | Kabale University |
| issn | 1110-662X |
| language | English |
| publishDate | 2006-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | International Journal of Photoenergy |
| spelling | doaj-art-5741909781b04008a7f6964ab6052a082025-02-03T07:26:01ZengWileyInternational Journal of Photoenergy1110-662X2006-01-012006The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds<p>The excited state structural relaxation of <mml:math alttext="$4$"> <mml:mn>4</mml:mn> </mml:math>-dimethylaminobenzenes with various <emph>para</emph>-acceptor substituents having double-band emission, local excited (LE) and charge transfer (CT), has been investigated. Fluorescence measurements at different temperatures and in different solvents have confirmed the existence of viscosity-dependent, temperature, and polarity-activated relaxation. The kinetics analysis has shown that the radiative deactivation rate constants of the individual LE and CT states differ by <mml:math alttext="$7$"> <mml:mn>7</mml:mn> </mml:math>–<mml:math alttext="$112$"> <mml:mn>112</mml:mn> </mml:math>-fold. The dipole moment changes at the excitation for CT states are significantly larger than those for LE states. The spectral-kinetics behavior of compounds studied agrees with the models <mml:math alttext="$ext{A} ightarrowext{A}^ast ightarrowext{B}^ast$"> <mml:mrow> <mml:mtext>A</mml:mtext><mml:mo>→</mml:mo><mml:msup> <mml:mtext>A</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> <mml:mo>→</mml:mo><mml:msup> <mml:mtext>B</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:mrow> </mml:math> or <mml:math alttext="$ext{A} ightarrowext{A}^astleftrightarrowext{B}^ast$"> <mml:mtext>A</mml:mtext><mml:mo>→</mml:mo><mml:msup> <mml:mtext>A</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> <mml:mo>↔</mml:mo><mml:msup> <mml:mtext>B</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:math>, where <mml:math alttext="$ext{A}^{ast}$"> <mml:msup> <mml:mtext>A</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:math> is the local excited planar and <mml:math alttext="$ext{B}^{ast}$"> <mml:msup> <mml:mtext>B</mml:mtext> <mml:mo>∗</mml:mo> </mml:msup> </mml:math> is the relaxed twisted state of the molecule. The rate constants of the twisted state formation have been calculated in the temperature range <mml:math alttext="$293$"> <mml:mn>293</mml:mn> </mml:math>–<mml:math alttext="$77$"> <mml:mn>77</mml:mn> </mml:math> K. The activation energies of forward process for compounds studied have been estimated.</p>http://www.hindawi.com/GetArticle.aspx?doi=10.1155/IJP/2006/81896 |
| spellingShingle | The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds International Journal of Photoenergy |
| title | The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds |
| title_full | The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds |
| title_fullStr | The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds |
| title_full_unstemmed | The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds |
| title_short | The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds |
| title_sort | dynamics of excited state structural relaxation of 4 dimethylaminobenzonitrile dmabn and related compounds |
| url | http://www.hindawi.com/GetArticle.aspx?doi=10.1155/IJP/2006/81896 |