Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Theoretical study of light-molecule nonlinear interactions
KTH, School of Biotechnology (BIO).
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The work presented in the thesis concerned theoretical study of light-matter nonlinear interactions. Two important aspects of such interactions have been examined, namely the nonlinear optical properties of a series of organic charge transfer molecules in solutions induced by the laser light and the propagation of the ultrafast high power laser through the nonlinear molecular medium.

Special attention has been paid to understand the solvent effects on the two-photon absorption of a symmetrical diamino substituted distyrylbenzene chromophore, for which time-dependent density functional theory in combination with polarizable continuum model (PCM) have been employed. The dielectric medium alone has a rather small effect both on the bond length alternation and on the one-photon absorption spectrum, but noticeable effects on the two-photon absorption cross section. Both one- and two-photon absorptions are found to be extremely sensitive to the planarity of the molecule. Our calculations indicate that the experimentally observed anomalous solvent effect on the two-photon absorption of dialkylamino substituted distyrylbenzene chromophores can not be attributed to the intrinsic properties of a single molecule and its interaction with solvents. With the same theoretical approaches, two-photon absorption properties of interacting polar chromophores have been investigated to examine the validity of the widely used exciton model. Our first principles calculations have shown that the exciton model offers a conceptually simple interpretation for experimental observations, but is lack of predictability.

The second part of the thesis is to investigate the propagation of ultrashort laser pulse through a one-dimensional asymmetric organic molecular medium by solving full Maxwell-Bloch equations using predictor-corrector finite-difference time-domain method. It focuses on the supercontinuum generation of spectra and the formation of attosecond pulses. It is shown that the supercontinuum generation is strongly modulated by both area and width of the pulse, which results from the interference between the splitting pulses in time-domain and is the implication of the time-energy uncertainty relation. The presence of permanent dipole moment in molecular medium has noticeable effects on the supercontinuum generation. Our calculations show that a well-shaped 132 attosecond pulse can be generated from a two femtosecond incoming pulse under certain conditions. Influences of carrier-envelope phase and time-dependent ionization on the spectral and temporal evolutions of the ultrashort pulses have also been discussed.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , 49 p.
National Category
Industrial Biotechnology
Identifiers
URN: urn:nbn:se:kth:diva-4364ISBN: 978-91-7178-642-5 (print)OAI: oai:DiVA.org:kth-4364DiVA: diva2:11964
Presentation
2007-05-16, FD41, AlbaNova, Stockholm, 10:10
Opponent
Supervisors
Note
QC 20101122Available from: 2007-05-10 Created: 2007-05-10 Last updated: 2011-11-23Bibliographically approved
List of papers
1. Solvent effects on two-photon absorption of dialkylamino substituted distyrylbenzene chromophore
Open this publication in new window or tab >>Solvent effects on two-photon absorption of dialkylamino substituted distyrylbenzene chromophore
Show others...
2007 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 126, no 20Article in journal (Refereed) Published
Abstract [en]

Solvent effects on the two-photon absorption of a symmetrical diamino substituted distyrylbenzene chromophore have been studied using the density functional response theory in combination with the polarizable continuum model. It is shown that the dielectric medium has a rather small effect both on the bond length alternation and on the one-photon absorption spectrum, but it affects significantly the two-photon absorption cross section. It is found that both one- and two-photon absorptions are extremely sensitive to the planarity of the molecule, and the absorption intensity can be dramatically reduced by the conformation distortion. It has led to the conclusion that the experimentally observed anomalous solvent effect on the two-photon absorption of dialkylamino substituted distyrylbenzene chromophores cannot be attributed to the intrinsic properties of a single molecule and its interaction with solvents.

Keyword
density-functional theory, polarizable continuum model, cross-sections, organic chromophores, electronic-structure, molecules, derivatives
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-13829 (URN)10.1063/1.2740641 (DOI)000246891700037 ()2-s2.0-34249864511 (Scopus ID)
Note
QC 20100630Available from: 2010-06-30 Created: 2010-06-30 Last updated: 2017-12-12Bibliographically approved
2. Two-photon absorbation activities of interating dipolar chromophores: a DFT study.
Open this publication in new window or tab >>Two-photon absorbation activities of interating dipolar chromophores: a DFT study.
(English)Manuscript (preprint) (Other academic)
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-26319 (URN)
Note
QC 20101122Available from: 2010-11-22 Created: 2010-11-22 Last updated: 2010-11-22Bibliographically approved
3. Modulation of supercontinuum generation and formation of an attosecond pulse from a generalized two-level medium
Open this publication in new window or tab >>Modulation of supercontinuum generation and formation of an attosecond pulse from a generalized two-level medium
2007 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, 1523-1534 p.Article in journal (Refereed) Published
Abstract [en]

The propagation of ultrashort pulses in a generalized two- level system, consisting of permanent dipole moments, is simulated by solving the full Maxwell - Bloch equations. Special attention has been paid to the supercontinuum generation of spectra and the formation of attosecond ( as) pulses. It is found that the supercontinuum generation is strongly modulated by both area and width of the pulse, resulting from the interference between the splitting pulses in the time domain and the implication of the time - energy uncertainty relation. The effect of the permanent dipole moment on the supercontinuum generation is discussed in detail. Calculations show that a well- shaped 132 as pulse can be generated from a 2 fs incoming pulse under the condition where the permanent dipole moment difference between two levels is equal to the transition dipole moment between them. Influences of carrier- envelope phase and time- dependent ionization on the spectral and temporal evolution of the ultrashort pulses are also discussed at length.

Keyword
femtosecond optical pulses, laser-pulses, ionization
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-11458 (URN)10.1088/0953-4075/40/8/006 (DOI)000246010300007 ()2-s2.0-34247138000 (Scopus ID)
Note
QC 20100630Available from: 2009-11-11 Created: 2009-11-11 Last updated: 2017-12-12Bibliographically approved

Open Access in DiVA

fulltext(435 kB)691 downloads
File information
File name FULLTEXT01.pdfFile size 435 kBChecksum SHA-1
b1bec3cdf64c947d9851e011b58897e8bbeffbe331b9f290a09747e7077994cd5f4d4cf6
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Zhao, Ke
By organisation
School of Biotechnology (BIO)
Industrial Biotechnology

Search outside of DiVA

GoogleGoogle Scholar
Total: 691 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 429 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf