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2009

Molecules

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

Acoustically Driven Oscillations Of Freely Suspended Liquid Crystal Filaments, J. Petzold, A. Nemes, A. Eremin, C. Bailey, N. Diorio, Antal Jakli, R. Stannarius Jul 2009

Acoustically Driven Oscillations Of Freely Suspended Liquid Crystal Filaments, J. Petzold, A. Nemes, A. Eremin, C. Bailey, N. Diorio, Antal Jakli, R. Stannarius

Antal Jakli

Some liquid crystalline phases of bent-core mesogens are known to form stable freely-suspended filaments with length to diameter ratios of 1000 and larger. These structures can behave like thin liquid chords. We study filament oscillations excited with harmonic sound waves. From amplitudes of the filament motion and phase shifts respective to the harmonic excitation signal we develop a model for the filament dynamics. Like in solid chords, the resonance frequency f(0) is inversely proportional to their length. The dependence of f(0) upon the filament radius allows one to draw conclusions on the nature of the filament tension. For thin filaments, …

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Quantitative Rescattering Theory For High-Order Harmonic Generation From Molecules, Anh-Thu Le, R. R. Lucchese, S. Tonzani, Toru Morishita, C. D. Lin Jul 2009

Quantitative Rescattering Theory For High-Order Harmonic Generation From Molecules, Anh-Thu Le, R. R. Lucchese, S. Tonzani, Toru Morishita, C. D. Lin

Physics Faculty Research & Creative Works

The quantitative rescattering theory (QRS) for high-order harmonic generation (HHG) by intense laser pulses is presented. According to the QRS, HHG spectra can be expressed as a product of a returning electron wave packet and the photorecombination differential cross section of the laser-free continuum electron back to the initial bound state. We show that the shape of the returning electron wave packet is determined mostly by the laser. The returning electron wave packets can be obtained from the strong-field approximation or from the solution of the time-dependent Schrödinger equation (TDSE) for a reference atom. The validity of the QRS is …

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Probing Molecular Frame Photoionization Via Laser Generated High-Order Harmonics From Aligned Molecules, Anh-Thu Le, R. R. Lucchese, M. T. Lee, C. D. Lin May 2009

Probing Molecular Frame Photoionization Via Laser Generated High-Order Harmonics From Aligned Molecules, Anh-Thu Le, R. R. Lucchese, M. T. Lee, C. D. Lin

Physics Faculty Research & Creative Works

Present experiments cannot measure molecular frame photoelectron angular distributions (MFPAD) for ionization from the outermost valence orbitals of molecules. We show that the details of MFPAD can be retrieved with high-order harmonics generated by infrared lasers from aligned molecules. Using accurately calculated photoionization transition dipole moments for fixed-in-space molecules, we show that the dependence of the magnitude and phase of the high-order harmonics on the alignment angle of the molecules observed in recent experiments can be quantitatively reproduced. This result provides the needed theoretical basis for ultrafast dynamic chemical imaging using infrared laser pulses.

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Spectroscopy Of Prebiotic Molecules Formed From O(1D) Insertion Reactions, Thomas A. Anderson, Jay A. Kroll, Susanna L. Widicus Weaver Jan 2009

Spectroscopy Of Prebiotic Molecules Formed From O(1D) Insertion Reactions, Thomas A. Anderson, Jay A. Kroll, Susanna L. Widicus Weaver

Thomas A. Anderson

Many important molecules in astrochemistry are unstable or reactive species, and therefore difficult to study in the lab. Three such molecules are methoxymethanol (CH3OCH2OH), methanediol (HOCH2OH), and aminomethanol (NH2CH2OH). These molecules are predicted to form on grain surfaces in the initial steps of interstellar prebiotic molecular evolution. These molecules are thought to be precursors to complex molecules such as sugars and amino acids. To test these prebiotic interstellar chemical pathways, a pure rotational spectrum is required for comparison to interstellar line surveys. Given the reactivity and instability of these molecules …

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Organic Bionics: Molecules, Materials And Medical Devices, Gordon G. Wallace, Simon E. Moulton Jan 2009

Organic Bionics: Molecules, Materials And Medical Devices, Gordon G. Wallace, Simon E. Moulton

Australian Institute for Innovative Materials - Papers

The uses of bionic devices that can improve the quality of human life are presented. Significant among them are the bionic ear or the bionic eye which has helped to regain use of important sensory organs. Bionics is the use of a biological entity and electronic devices that are put together to create the required implant.

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Molecules With Multiple Personalities: How Switchable Materials Could Revolutionise Chemical Sensing, Fernando Benito-Lopez, R Byrne, Yizhen Wu, Lorrain Nolan, Jung Ho Kim, King Tong Lau, Gordon G. Wallace, Dermot Diamond Jan 2009

Molecules With Multiple Personalities: How Switchable Materials Could Revolutionise Chemical Sensing, Fernando Benito-Lopez, R Byrne, Yizhen Wu, Lorrain Nolan, Jung Ho Kim, King Tong Lau, Gordon G. Wallace, Dermot Diamond

Australian Institute for Innovative Materials - Papers

Worldwide, the demand for sensing devices that can conform with the requirements of large-scale wireless sensor network (WSN) deployments is rising exponentially. Typically, sensors should be very low cost, low power (essentially self-sustaining), yet very rugged and reliable. At present, functioning WSN deployments involve physical transducers only, such as thermistors, accelerometers, photodetectors, flow meters, to monitor quantities like temperature, movement, light level and liquid level/flow. Remote, widely distributed monitoring of molecular targets remains relatively unexplored, except in the case of targets that can be detected directly using 'non-contact' techniques like spectroscopy. This paper will address the issues inhibiting the close …

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Molecular Modeling Of Para-Benzyne And A Series Of Push-Pull [14]-Pyridoannulenes, Evan B. Wang Jan 2009

Molecular Modeling Of Para-Benzyne And A Series Of Push-Pull [14]-Pyridoannulenes, Evan B. Wang

Honors Theses

Molecular modeling is vital for gaining insight into experimental results and discovering molecular properties not yet characterized by experiment. Depending on the type of molecule under investigation, certain methods will yield more accurate and revealing answers. In the first project, a state-averaged, multireference complete active space (CAS) approach was used for the determination of the vertical excitation energies of valence and Rydberg states of para-benzyne. Orbitals were generated with a 10- and 32-state averaged multiconfigurational self consistent field (MCSCF) approach. Electron correlation was included using multireference configuration interaction with singles and doubles (MR-CISD), including Pople correction for size extensivity (MR-CISD+Q), …

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