排序方式: 共有24条查询结果,搜索用时 31 毫秒
1.
FTIR photothermal beam deflection (PBD) spectroscopy was used to record PBD spectra of IR-absorbing gases in presence of IR-absorbing and non-absorbing solids. The presence of the solid, IR-absorbing or not, causes asymmetry at the juncture of the IR and probe laser 相似文献
2.
Experimental method for measuring photoacoustic(PA) signals generated by a pulsed laser beam in liquids is described. The
pulsed PA technique is found to be a convenient and accurate method for determination of quantum yield in fluorescent dye
solutions. Concentration dependence of quantum yield of rhodamine 6G in water is studied using the above method. The results
indicate that the quantum yield decreases with increase in concentration in the quenching region in agreement with the existing
reports based on radiometric measurements. 相似文献
3.
4.
S. A. Martin Britto Dhas M. Suresh P. Raji K. Ramachandran S. Natarajan 《Crystal Research and Technology》2007,42(2):190-194
Photoacoustic spectroscopy (PAS) is a non‐destructive testing (NDT) tool and used here for analyzing the physical properties such as thermal diffusivity, thermal diffusion length, thermal conductivity and thermal effusivity of L‐Threonine and L‐Prolinium tartrate. These two crystals belong to a group of recently developed NLO materials, in our laboratory. The single crystals of the two compounds were grown by using submerged seed solution growth method. Characterization of the crystals was made by using single crystal X‐ray diffraction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
F. Firszt K. Strzakowski A. J. Zakrzewski S. gowski H. Mczyska A. Marasek 《Crystal Research and Technology》2007,42(12):1352-1358
Zn1‐x‐yBexMnySe solid solutions were grown from the melt by the high pressure Bridgman method. Optical, luminescence, photoelectric and photothermal properties of this material were investigated. Interpretation of the piezoelectrically detected photoacoustic spectra was performed using Jackson and Amer theory. From the spectral dependence of the amplitude and phase of photoacoustic signal as well as from photoluminescence spectra the variation of energy gap with composition was determined. The values of thermal diffusivity were derived from the dependence of photoacoustic signal on modulation frequency of the laser radiation illuminating the sample. The photoluminescence‐excitation spectra and photoconductivity spectra were measured. The origin of luminescence in Zn1‐x‐yBexMnySe was discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
Sajan D. George Rajesh Komban K.G.K. Warrier P. Radhakrishnan V.P.N. Nampoori C.P.G. Vallabhan 《哲学杂志》2013,93(6):717-729
A laser-induced photoacoustic technique was employed to investigate thermal transport through nanocrystalline CePO4 samples prepared via the sol–gel route. Evaluation of thermal diffusivity was carried out using the one-dimensional model of Rosencwaig and Gersho for the reflection configuration of the photoacoustic method. Structural analyses of samples revealed that they are nanoporous in nature, possessing micron-sized grains. Analysis of results shows that thermal diffusivity value varies with sintering temperature. Results are explained in terms of the variation in porosity with sintering temperature and the effects of various scattering mechanisms on the propagation of phonons through the nanoporous ceramic matrix. Further analyses confirm that apart from porosity, grain boundary resistance and interface thermal resistance influence the effective value of thermal diffusivity of the samples under investigation. 相似文献
7.
Kira V. Khmelnytskaya Ibrahim Serroukh 《Mathematical Methods in the Applied Sciences》2013,36(14):1878-1891
A method for studying the one‐dimensional heat transfer process within an inhomogeneous spatially bounded medium in the presence of an external heat source is presented. It is based on a recently introduced technique for solving problems related to Sturm–Liouville equations that consists in the representation of solutions in the form of a spectral parameter power series. We consider a heat transfer model linked to photoacoustic and show that the introduced method, besides its relative simplicity and analytical nature, offers an efficient numerical algorithm as well as a convenient way to work separately with different physically meaningful components of the temperature distribution function. Detailed explanations and numerical examples are given. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
The interaction of 8-methoxypsoralen (8-MOP) with synthetic eumelanin was investigated using static and time-resolved fluoresence and pulsed photoacoustic calorimetry. Spectroscopic data indicate the absence of interaction in the ground state, whereas the singlet excited state of 8-MOP is quenched by the pigment; the average fluorescence lifetimes are independent of the melanin concentration, thus indicating a static mechanism. Photoacoustic data show that the quenching process involves an increased intersystem crossing probability, which is almost unaffected by the presence of oxygen, as expected for a molecule essentially acting as a type I photosensitizing agent. 相似文献
9.
The acoustic signals generated in solids due to interaction with pulsed laser beam is used to determine the ablation threshold
of bulk polymer samples of teflon (polytetrafluoroethylene) and nylon under the irradiation from a Q-switched Nd:YAG laser
at 1.06μm wavelength. A suitably designed piezoelectric transducer is employed for the detection of photoacoustic (PA) signals generated
in this process. It has been observed that an abrupt increase in the amplitude of the PA signal occurs at the ablation threshold.
Also there exist distinct values for the threshold corresponding to different mechanisms operative in producing damages like
surface morphology, bond breaking and melting processes at different laser energy densities. 相似文献
10.
Coupling near‐infrared (NIR) nanoscale absorbing materials with microbubbles (MBs) can generate a multifunctional dual imaging contrast agent. A new approach is presented for a hybrid photoacoustic/ultrasound contrast enhancer where pristine graphene is stably tethered to poly(vinyl alcohol) (PVA)‐based MBs. The main advantages of this approach are i) the preservation of optical and mechanical properties of intact graphene for an efficient photoacoustic (PA) enhancement and ii) the echogenicity and biocompatibility due to the robust anchoring of graphene to the bioinert PVA shell. PVA MBs provide ideal platforms for drug loading and ligand tethering for specific tumor targeting. One of the crucial goals toward this direction is optimizing this system in terms of balance between favorable acoustic/photoacoustic properties, immune shielding, and cytotoxicity. Such a combination strongly depends on the bridging moieties between graphene and the microbubble surface and can be easily tuned by PEGylation. The optimized graphene PVA MBs as contrast agent provide an efficient enhancement in vivo both in ultrasound and photoacoustic modes. The spectrally separable absorbance profile allows to a first demonstration of performing real‐time in vivo multiplexed photoacoustic imaging of graphene PVA MBs, and assessment of their full body biodistribution using a Vevo LAZR‐X photoacoustic imaging system. 相似文献