Investigation of Micellar Effects in Thermal Lens Spectrophotometry

The effect of micellar solutions in thermal lens spectrophotometry was investigated. Several aspects of the thermal lens signal including the formation rate and the relaxation of the thermal lens were compared in various neat solvents and in aqueous micellar solutions. The experiments were performed with a double-beam thermal lens apparatus based upon a pulsed-dye laser as the excitation beam and a He-Ne laser as the probe beam. The results show that, if micellar solutions can be used to solubilize hydrophilic species in solvents having better thermo-optical properties than water, they do not provide sensitive modifications of the thermo-optical properties of water. The absence of micellar effect in thermal lensing, in comparison to the well-known micellar enhanced fluorescence, is discussed with respect to the size of micelles and micellar dynamics, the photophysical processes associated with thermal lensing, and the time dependence of the thermal lens signal.

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Use of thermal lens spectrometry for the investigation of dimerization equilibria of rhodamine 6G in water and aqueous micellar solutions

Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy ◽

10.1016/s0584-8539(97)00027-5 ◽

1997 ◽

Vol 53 (9) ◽

pp. 1419-1430 ◽

Cited By ~ 27

Author(s):

M Fischer ◽

J Georges

Keyword(s):

Thermal Lens ◽

Rhodamine 6G ◽

Micellar Solutions ◽

Thermal Lens Spectrometry ◽

Aqueous Micellar Solutions

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Development of a Multiwavelength Thermal Lens Spectrophotometer Based on an Acousto-Optic Tunable Filter as a Polychromator

Applied Spectroscopy ◽

10.1366/0003702944027679 ◽

1994 ◽

Vol 48 (1) ◽

pp. 101-106 ◽

Cited By ~ 12

Author(s):

Chieu D. Tran ◽

Ricardo J. Furlan ◽

Jian Lu

Keyword(s):

Detection Limit ◽

Thermal Lens ◽

Laser Light ◽

Limit Of Detection ◽

Tunable Filter ◽

Lanthanide Ions ◽

Probe Laser ◽

Excitation Beam ◽

Thermal Lens Signal ◽

Rf Signals

Instrumentation development of a novel multiwavelength thermal lens spectrophotometer which has the capability of achieving truly multiwavelength excitation is described. The spectrophotometer is based on a new concept by which the sample is excited by multiwavelength excitation beams simultaneously, not sequentially as in previously reported multiwavelength thermal lens apparatus. This was accomplished by use of the acousto-optic tunable filter (AOTF) as a polychromator. Specifically, four different rf signals were simultaneously applied to the filter to enable it to diffract incident multiline laser light into a beam which contained four different wavelengths. This multiwavelength beam was then used to excite the sample, and the corresponding thermal lens signal was measured by a He-Ne probe laser. Compared with other multiwavelength thermal lens instruments, this all-solid-state thermal lens spectrophotometer has advantages that include its ability to simultaneously analyze multicomponent samples in microsecond times scale, without the need for any prior sample preparation. With this apparatus and with the use of a 12-mW multiwavelength excitation beam, the limit of detection for four-component (lanthanide ions) samples is estimated to be 10−6 cm−1, which is similar to the detection limit obtained for one-component samples with the use of a single-wavelength system.

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Continuous-Wave-Laser versus Pulsed-Laser Excitation for Crossed-Beam Photothermal Detection in Small Volume Applications: Comparative Features

Applied Spectroscopy ◽

10.1366/0003702055012645 ◽

2005 ◽

Vol 59 (9) ◽

pp. 1103-1108 ◽

Cited By ~ 1

Author(s):

Joseph Georges

Keyword(s):

Thermal Lens ◽

Small Volume ◽

Continuous Wave ◽

Laser Excitation ◽

Pulsed Laser ◽

Beam Waist ◽

Continuous Wave Laser ◽

Excitation Beam ◽

Cw Laser ◽

Thermal Lens Signal

Crossed-beam thermal lens spectrometry can be implemented using continuous-wave- (cw) laser or pulsed-laser excitation. In both cases, the signal depends on the position of the sample with respect to the probe beam waist, the size of the excitation beam, the beam-size ratio into the sample, and the power or energy of the excitation beam. However, due to differences in the rate of formation and relaxation of the thermal lens, both methods exhibit distinct key features. Optimization of the experimental setup and understanding the thermal lens signal are more complicated under cw-laser excitation than with pulsed-laser excitation. Unlike that observed under pulsed excitation, the effect of the excitation beam waist, of the sample size, and of the flow rate are closely related to the effective size of the thermal element and depend on the chopping frequency. Although the intrinsic sensitivities are almost the same, the performance can significantly differ depending on the chopping frequency or pulse repetition rate, which should be high enough to allow fast data collection and efficient signal averaging.

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Optically Detected Magnetic Resonance and Double Beam Photoluminescence of CdS/HgS/CdS Nanoparticles

MRS Proceedings ◽

10.1557/proc-536-257 ◽

1998 ◽

Vol 536 ◽

Author(s):

H. Porteanu ◽

A. Glozman ◽

E. Lifshitz ◽

A. Eychmüller ◽

H. Weller

Keyword(s):

Optical Properties ◽

Magnetic Resonance ◽

Cds Nanoparticles ◽

Electron Hole ◽

Cladding Layer ◽

Double Beam ◽

Optically Detected Magnetic Resonance ◽

Optically Detected ◽

Cladding Layers ◽

Hole Recombination

AbstractCdS/HgS/CdS nanoparticles consist of a CdS core, epitaxially covered by one or two monolayers of HgS and additional cladding layers of CdS. The present paper describes our efforts to identify the influence of CdS/HgS/CdS interfaces on the localization of the photogenerated carriers deduced from the magneto-optical properties of the materials. These were investigated by the utilization of optically detected magnetic resonance (ODMR) and double-beam photoluminescence spectroscopy. A photoluminescence (PL) spectrum of the studied material, consists of a dominant exciton located at the HgS layer, and additional non-excitonic band, presumably corresponding to the recombination of trapped carriers at the interface. The latter band can be attenuated using an additional red excitation. The ODMR measurements show the existence of two kinds of electron-hole recombination. These electron-hole pairs maybe trapped either at a twin packing of a CdS/HgS interface, or at an edge dislocation of an epitaxial HgS or a CdS cladding layer.

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