香荆芥酚的荧光光谱和吸收光谱研究

研究了中药活性成分香荆芥酚(Carvacrol)的荧光光谱和吸收光谱,依据光谱数据测量了香荆芥酚的电离常数和荧光量子产率.在pH＜2.0时,香荆芥酚的荧光随溶液pH增大而增强;在pH2.0～8.0范围内,香荆芥酚有稳定的强荧光,最大激发波长为278 nm,最大发射波长为306 nm; pH＞8.0时荧光强度随pH的增大...     

Structure-sensitive changes in the terahertz absorption spectra of merocyanine dye derivatives

The low-frequency vibrational modes of the series of merocyanines (malononitrile derivative) have been investigated by pulsed terahertz spectroscopy. The terahertz absorption spectra are shown to contain both intermolecular and intramolecular vibrational modes in the range of 0.15–3.45 THz (5–115 cm⁻¹). An unambiguous correlation is established between the purposeful modification of the molecular structure of merocyanine dyes and the change in their terahertz absorption spectra.     

Influence of surfactants on the fluorescence and absorption spectra of erythrosin in aqueous solution

The effect of certain non-ionic, anionic and cationic surfactants on the fluorescence and absorption spectra of erythrosin has been studied. Shifts towards longer wavelengths in absorption and fluorescence peaks have been observed. Also, there appears to be a marked enhancement in the fluorescence intensity of erythrosin on adding small amounts of surfactants. The shift in the absorption peak wavelength appears to be due to the binding of the surfactant with dye molecules. The enhancement in the fluorescence intensity is attributed to the disaggregation of erythrosin dye dimer and multimer forms into the monomeric form. The change in the geometry of dye molecules in the presence of cationic surfactants has also been discussed. Enhancement in the fluorescence intensity on the addition of ethanol has been observed.     

Understanding the absorption and emission spectra of borondipyrromethene dye and its substituted analogues

Borondipyrromethene (BODIPY) dye possesses a bright and long wavelength emitting fluorescent character with a wide spectral range from visible to near infrared region. In the present work, the spectral properties of BODIPY dyes were analyzed using ab intio and density functional theory methods. The ground and excited state geometries of BODIPY and its substituted analogues in chloroform medium, were optimized using the density functional theory (DFT) and singly excited configuration interaction (CIS) methods. Based on the ground and excited state geometries, the absorption and emission spectra have been calculated using time-dependent density functional theory (TDDFT) method. The TDDFT calculations have been performed using hybrid exchange correlation functionals B3LYP and M06-HF and long-range separated functionals LC-BLYP, LC-BOP, LC-PBE, LC-PBE0 and CAM-B3LYP. The solvent phase calculations were carried out using polarizable continuum model (PCM). The TDDFT investigation reveals that the substitution of acceptor, donor–donor, donor–acceptor–donor and phenyl group in BODIPY dye influence the absorption and emission spectra significantly.     

MOC染料单分子层薄膜聚集体的吸收光谱研究

用吸收光谱对染料的Langmuir-Blodgett(LB)膜的聚集体在不同条件下进行了研究.典型的染料1-methyl-1’-octadecy1-2,2’-cyaninperchlorate(MOC)LB膜聚集体的吸收峰(J带)在580nm附近,吸收为0.09.刚制备好的样品随时间而改变其吸收特性,表明聚集体的结构在2hr后才趋于稳定;测定了不同样品J带的参数;吸收峰值波长位置和峰的半宽度,以及这些参数随温度的变化.吸收随温度变化的可逆性是LB膜聚集体用作光记录介质的一个物理基础.温度超过100℃时,样品吸收的不可逆变化反映相变发生.     

Fluorescence quantum yield of rhodamine 101 in the presence of absorption saturation

Using the photothermal method we measure the fluorescence quantum yield of a rhodamine 101 solution in ethanol for different values of the pump-field fluence. Our experiments reveal a depletion of the fluorescence quantum yield as the pump fluence increases. To explain the observed fluorescence quenching, a dependence of the nonradiative relaxation rates on the field fluence is proposed. Predictions of the model are in good agreement with the experiments. Received: 16 November 1999 / Revised version: 5 July 2000 / Published online: 13 September 2000     

Fluorescence quenching of laser grade dye coumarin 440 in presence of hydrogen peroxide

Fluorescence quenching of coumarine 440 in ethanol due to the presence in aqueous solution of hydrogen peroxide is reported here. The Stern-Volmer plot is very much linear and quencher concentration could easily be estimated. An optical sensor for the detection of aqueous hydrogen peroxide could thus be easily constructed using the dye solution.     

Fluorescence and absorption spectra of binary mixtures of aromatic hydrocarbons in frozen crystalline solutions

The UV and visible spectra of frozen naphthalene-anthracene, naphthalene-naphthacene, and anthracenenaphthacene solutions have been studied. The effects of component concentrations on the spectra have been determined.In conclusion the authors express thanks to Prof. E. V.Shpol'skii for his constant attention to and interest in the work.     

Sensitive detection of flame absorption spectra of rare-earth elements with a dye laser

The dye-laser amplified absorption method is applied to observe the atomic absorption lines of rare-earth elements in a nitrous-oxide-acetylene flame. All of the rare-earth elements except Pm are analyzed and about 1200 lines have been recorded within the continuous spectral region from 432 to 670 nm. A much larger number of absorption lines can be detected than those measured by the traditional method. The absorption bands of monoxide molecules have also been detected.     

Fluorescence and absorption spectra of Tb3+ ions in yttrium-gallium garnet

The data on the fluorescence and absorption spectra of the Tb³⁺ ions in yttrium-gallium garnet in the region 3800–6800 Å have been obtained at 4.2 K and 77 K. The groups of fluorescence lines in the regions 3800–4830 Å and 4860–6800 Å have been assigned to transitions from ⁵D₃ and ⁵D₄, respectively, to the Stark components of ⁷F states. The analysis of the spectra led to the identification of six Stark components each for the ⁵D₃ and ⁵D₄ states and thirty-six components of ⁷F states. The local symmetry arround the Tb³⁺ ions is found to be orthorhombic, in accordance with the complete removal of the degeneracy of the ⁷F₅ and ⁷F₁ electronic states.     

Highly resolved electronic absorption and luminescence spectra of some phenanthrolines in Shpolskii matrices: Part II. Fluorescence and S1←S0 absorption spectra

Highly resolved fluorescence and S₁←S₀ absorption spectra of some phenanthrolines in n-alkane matrices were obtained at 77 K. The vibrational analysis of the spectra was carried out. Mirror symmetry distortions of the fluorescence and absorption spectra were attributed to vibronic coupling between ¹(π, π¹) states. It was shown that vibronic mixing of S₁(π, π¹) and S₂(π, π¹) states occurs in phenanthroline molecules with S₁-S₂ energy gap not exceeding 3000 cm^-1 (i.e., 4,7-, 1,7- and 1,10-Phen), whereas in other phenanthrolines the coupling of S₁ and S₃(π, π¹) plays a dominant role. Fluorescence quantum yields of phenanthroline liquid solutions were measured. Changes of luminescence efficiencies due to the change of the polarity of the media point to a weak coupling of the lowest ¹(π, π¹) and ¹(n, π¹) states.     

Fluorescence and absorption spectra of 9, 10-diazaphenanthrene solutions at 77°K

The S₁(n, √^*) ? S₀ fluorescence and absorption spectra of 9, 10-diazaphenanthrene solutions in hydrocarbons possess at 77°K a quasilinear structure (Shpolskii effect). In the frozen n-hexane matrix (c = 10^-4 M) the fluorescence spectrum displays a triplet structure (22 181, 22 169 and 22 149 cm^-1 for the O-O transition). The spectra of 9, 10-diazaphenanthrene solution are shifted towards the red compared with those of the single crystal (～ 900 cm^-1). A good agreement between the calculated and experimental values of this shift is obtained. A strong concentration effect on the structure of the spectra is discussed. A quasilinear structure is observed also in the second absorption band.     

Fluorescence lifetimes in colled dye matrices

Measurements are reported of the fluorescence lifetimes of Rhodamine 6G, Rhodamine B and dichloro-fluorescein in cooled dye matrices in the temperature range from +20°C to - 140°C.     

Premicellar and micelle formation behavior of aqueous anionic surfactants in the presence of triphenylmethane dyes: protonation of dye in ion pair micelles

The premicellar and micelle formation behaviors of four cationic triphenylmethane dyes, viz, Pararosaniline (RN), Crystal violet (CV), Ethyl violet (EV), and Malachite green (MG), in aqueous anionic surfactant solutions of sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and sodium dodecyl sulfonate (SDSN) have been studied by spectral and surface tension measurements. The study was carried out within a pH range where the dyes are stable in their quinoid forms. The dyes have been found to form dye–surfactant ion pairs (DSIPs) with the surfactants, at the surfactant concentrations well below their critical micelle concentration, CMC*. The DSIPs behave like nonionic surfactants and form an air–water interfacial monolayer. The DSIPs have a lower critical micelle concentration (CMC_IP), greater efficiency, and lower effectiveness than the corresponding pure surfactants. As the surfactant concentration is increased below the CMC*, the DSIPs start forming micelles of their own where the dye gets protonated and exists as a protonated dye–surfactant ion pair (PDSIP) in the ion pair micelles. As the concentration of the surfactant exceeds the CMC* of the pure surfactant, the protonation reverses gradually with the dye remaining in the micelles in solubilized form and the DSIPs in the air–water interfacial monolayer are replaced by pure surfactants. The distorted helical isomeric form (isomer B) of the dyes is favored in the PDSIPs. Copyright © 2009 John Wiley & Sons, Ltd.