The effect of the internal field on Raman scattering cross sections

Nestor, James R.; Lippincott, Ellis R.

doi:10.1002/jrs.1250010309

Cited by 120 publications

(68 citation statements)

References 34 publications

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“…We determine the difference in the PMV between the conformers from the pressure dependence of the Raman intensities. Assuming that the ratio of the scattering cross sections of the conformers is independent of pressure, 33 the volume difference between the conformers (⌬V) is given by Figure 7 shows the pressure dependence of the ratio for the integrated intensities between the conformers. ⌬V PII is defined as the difference in the PMV between the P II conformer and each conformer: ⌬V Table II.…”

Section: Pressure Effect On Conformationalmentioning

confidence: 99%

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Temperature and pressure effects on conformational equilibria of alanine dipeptide in aqueous solution

et al. 2004

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We investigated the temperature and pressure effects on conformational equilibria of N-acetyl-L-alanine-N'-methylamide (AAlaMA) in aqueous solution by Raman spectroscopy. Scattering intensities in the skeletal stretching mode of AAlaMA in aqueous solution were decomposed into some component bands by the spectra analysis. Our results indicate that each component band for AAlaMA adopts not only the P(II) and alpha(R) conformations but also the C(7eq) conformation. From temperature and pressure dependencies of the band intensities, we determined the enthalpy differences and the volume differences between the conformers. The C(7eq) conformer is enthalpically most stable due to the intramolecular hydrogen bond. The partial molar volume of the C(7eq) conformer is the smallest through the solvent-exclusion effect rather than the solute-solvent electrostatic interaction effect.

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Section: Pressure Effect On Conformationalmentioning

confidence: 99%

“…We determine the enthalpy differences between the conformers from the temperature dependence of the Raman intensities. Assuming that the ratio of the scattering cross sections of the conformers is independent of temperature, 33 the enthalpy difference between the conformers (⌬H) is given by…”

Section: Temperature Effect On Conformationalmentioning

confidence: 99%

Temperature and pressure effects on conformational equilibria of alanine dipeptide in aqueous solution

et al. 2004

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“…Among these, one can site the study of the amplification of the local field intensity in disordered metallic structures where the heterogeneities have sizes much smaller than the wavelength of the incident radiation [1], the analysis of photonic bandgap materials [2], or the effect of the internal field on Raman scattering cross sections [3]. Another interesting domain of application concerns the study of the optical properties of architectural paint films.…”

Section: Introductionmentioning

confidence: 99%

Local field intensity in aggregates illuminated by diffuse light: T matrix approach

Auger

Stout

2008

Appl. Opt.

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We derive an analytic expression for the local field intensity in an aggregate of particles illuminated by diffuse light (T matrix formalism). To be precise, the diffuse light average is obtained by averaging the electromagnetic response from plane waves over all possible incident field direction polarizations. We applied this new averaging formula to analyze variations in the electromagnetic couplings between two isotropic spheres as a function of their separation distance. The numerical calculations were performed with the recursive centered T matrix algorithm (RCTMA), one of the known analytical solutions of the multiple scattering equation of light. Illustrative calculations clearly demonstrate that diffuse averaging has a large smoothing effect on the strong angular and local variations in the field intensities that are omnipresent in orientation fixed calculations. We believe that this formalism can be a valuable tool in the analysis of electromagnetic couplings in dense random heterogeneous media, in which light propagation is dominated by a scalar diffusion behavior.

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“…Por outro lado, o fato de o espalhamento Raman ser um processo muito pouco eficiente -devido à sua pequena seção de choque (cerca de 10 -30 cm 2 Sr -1 molécula -1 ) 8 -faria da espectroscopia Raman uma técnica pouco sensível. Entretanto, a presença de superfícies metálicas nanoestruturadas apresenta a propriedade de intensificar o sinal Raman de moléculas adsorvidas por fatores da ordem de 10 6 vezes.…”

Section: Introductionunclassified

Preparação e caracterização de substratos SERS ativos: um estudo da adsorção do cristal violeta sobre nanopartículas de prata

Santana¹,

Zaia²,

Cório³

et al. 2006

Quím. Nova

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Recebido em 26/7/04; aceito em 30/6/05; publicado na web em 20/1/06 PREPARATION AND CHARACTERIZATION OF SERS-ACTIVE SUBSTRATES: A STUDY OF THE CRYSTAL VIOLET ADSORPTION ON SILVER NANOPARTICLES. The structural characterization of molecules used in the sterilization of blood for transfusions, such as crystal violet (CV), is relevant for understanding the action of these prophylactic drugs. The characterization is feasible by surface enhanced resonance Raman spectroscopy (SERRS) of CV in solution or on surfaces. The limit of detection of CV by SERRS, in the presence of colloidal particles, using 514.5 nm as excitation radiation, was found to be around 1 ppb. The characterization of CV was also made by SERS, by using different active-particles-containing substrates, proving the versatility of this technique for the study of such structures. The results suggest that the controlled production of highly efficient SERS-active substrates may allow qualitative and quantitative analysis, with high sensitivity, with potential applications in medical and environmental fields.Keywords: silver sol; crystal violet; surface enhanced resonance Raman spectroscopy (SERRS). INTRODUÇÃOCertas parasitoses estão entre as mais prevalentes doenças do mundo, atingindo milhões de pessoas. A prevenção destas doenças depende de medidas sanitárias, assim como do emprego de fármacos antiparasitários eficazes e seguros. Um importante exemplo é a doença de Chagas, que afeta aproximadamente 16-18 milhões de pessoas, principalmente nas Américas do Sul e Central, constituindo um sério problema de saúde pública. Desde a descoberta da doença pelo médico sanitarista Carlos Chagas, em 1909, até os dias atuais, foram realizadas inúmeras tentativas de tratamento, sem que fosse obtido um medicamento totalmente eficaz. Para eliminação do parasita do sangue contaminado em bancos de sangue, a única substância utilizada como agente quimioprofilático é o cristal violeta (CV), também conhecido como violeta de genciana. Quando essa substância é adicionada ao sangue estocado na concentração de 250 μg/mL, promove eliminação segura das formas infectantes. Porém, seu uso também é limitado pelos efeitos colaterais e pela cor transferida à pele e à urina dos pacientes transfundidos 1 .Para desenvolvimento de fármacos mais seletivos e eficazes é cada vez mais importante a seleção do alvo terapêutico, o que permite uma busca racional por agentes que provoquem a resposta desejada e especí-fica para o controle da doença. A forma como o parasita causador da doença de Chagas (Trypanosoma cruzi) relaciona-se com a molécula de cristal violeta demanda um estudo visando a identificação desta interação. Conhecer os mecanismos envolvidos nessa relação favorece o desenvolvimento de novas terapias para combater a doença. No caso do cristal violeta ou violeta de genciana suas reações são pouco estudadas, demonstrando a complexidade deste composto da classe dos corantes trifenilmetânicos 2,3 .Freqüentemente são utilizados para análise dos corantes os mé-todos cromatográficos 4,5 , com...

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The effect of the internal field on Raman scattering cross sections

Cited by 120 publications

References 34 publications

Temperature and pressure effects on conformational equilibria of alanine dipeptide in aqueous solution

Temperature and pressure effects on conformational equilibria of alanine dipeptide in aqueous solution

Local field intensity in aggregates illuminated by diffuse light: T matrix approach

Preparação e caracterização de substratos SERS ativos: um estudo da adsorção do cristal violeta sobre nanopartículas de prata

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