Irradiation by laser

Figure 18 Comparison of optical absorption data and TEM images (at the same magnification) for two gold samples irradiated by laser pulses having the same fluence (0.25 J cm ) and different pulse width. Top with a 7-nsec laser pulse at 800 nm. (a) Partial melting of the gold nanorods and (b) selective optical hole burning in the near-IR band corresponding to the nanorods. Bottom with laser pulses of 100 fsec. (c) Complete melting of the gold nanorods into nanodots and (d) complete depletion of the nanorod band. (From Ref 211.)...

Figure 9.19 The population evolution in the and 5, manifold of states, Pg (t) (a,b) and (t) (c,d), respectively, of the 5q 5j process under irradiation by laser pulses with ]jrofiles as shown...

Since stationary electrodes are employed in most SERS experiments, a relatively small number of adsorbed molecules are continuously irradiated by laser beams. When exciting lines are within strong absorption bands of the adsorbed species, surface-enhancement resonance Raman spectra (SERRS) are obtained. However, this may lead to decomposition of such species due to local heating. Use of a cylindrical rotating electrode can circumvent this problem (57). 

The aim of this work was to study the chemiluminescence of CLA and MCLA in various ROS generating systems and use it in the photodynamic system (e.g. phthalocyanines, chlorophyll a) after irradiation by laser. 

Fig. 8 UV spectra recorded after irradiation of MP1 and TM1 in THF. 1.2 ml of solution (ca. 1(T5 M) was irradiated by laser pulses with energy of 110 mj REPRINTED WITH PERMISSION OF [Ref. 82], COPYRIGHT (2001) American Chemical Society...

Fig. 2. Experimental setup of the pump-probe experiment showing the molecular beam irradiated by laser pulse sequences coming from a titanium sapphire fs-laser system. The resulting photoions are detected by a quadrupole mass spectrometer.

A Raman spectrophotometer was used to measure in situ the polymerisation rate of acrylamide photoinitiated by hydrogen chromate anion in aqueous solution upon irradiation by laser beam (ionised argon)... 

A Raman spectrophotometer was used to measure in situ the polymerisation rate of acrylamide photoinitiated by hydrogen chromate anion in aqueous solution upon irradiation by laser beam (ionised argon). The progress of the reaction was monitored at 2930/cm, the absorption characteristic of the polymer formed. The method was found to be reliable, but is limited to monomers whose polymer is soluble in the reaction medium. 10 refs. EUROPEAN COMMUNITY FRANCE WESTERN EUROPE... 

Thanks to the development of thin, flexible optical fibers with a high damage threshold for the radiation [1562, 1563], inner organs of the human body, such as the stomach, bladder, gallbladder or kidneys, can be selectively irradiated by laser radiation. A new technique for breaking kidney stones to pieces by irradiation with pulsed lasers (laser lithotripsy) has found increasing interest because it has several advantages compared to the ultrasonic shockwave lithotripsy [1564—1566]. 

Centrifugal Flow Control, Fig. 2 Schematic of active valves sealing a microchannel (a) irradiation by laser (b) and opening of the microchannel (c) ferrooxide particles... 

The forward spectrum of sodium at density of 1.8 10 cm irradiated by laser with frequency loi to the blue of the D2 transition is shown in figure 1. This spectrum contains, in addition to the laser radiation, a spectrally broad off-axis conical emission attributed by us to a Cherenkov-type emission, and a narrow coherent peak to the blue of the Di transition - the "blue peak". This spectrally narrow emission is on-axis and has a threshold on the laser intensity. Thus, this emission is a stimulated one. Within the resolution of our spectrometer, its frequency does not depend on the laser detuning from the D2 transition. 

FIGURE 5.10 Two-color lambda-type photoassociation spectroscopy of Rb2- Colliding, trapped ultracold Rb atoms are irradiated by lasers of frequencies vj and V2- Spontaneous emission from the excited level at frequency leads to loss of the atoms from the trap. Optical-optical double-resonance signals (free-bound-bound) are observed when the frequency difference V2 — vj coincides with the binding energy of a lower-state vibrational level. (From Tsai, C.C. et al., Phys. Rev. Lett, 79,1245, 1997. With permission.)... 

Laser-induced interstitial thermotherapy represents a minimally invasive therapy, where the cancerous tissue is irradiated by laser light guided through an optical fiber. Planning the operation anticipates the knowledge of the absorption and scattering properties of cancerous tissue compared to healthy tissue. Several optical and computational techniques have been developed that can... 

Upon irradiation by laser light, the initiator molecule changes its stereochemical configuration from the trans to the cis isomer. This cis/trans isomerism becomes of importance if azoinitiators are employed in pulsed laser experiments The time at which the laser pulse hits the reaction mixture is no longer identical with the generation of the primary radicals. The time delay is usually in the order of microseconds and may be observed in time-resolved pulsed laser experiments. 

The Si-SiO core-shell nanocomposite is prepared by a sol-gel method in combination with a subsequent heat-treatment process. At first, molten Si with high purity was irradiated by laser and gasified under an Ar atmosphere, and the condensed Si nanoparticles were collected on a water-cooled wall. Then, the obtained Si nanoparticles were dipped into a stirred tetraethylorthosilane (TEOS) sol, followed by the processes of pH adjustment, aging, drying, and heat treatment. Finally, a core-shell structured Si-SiO nanocomposite was synthesized. Because the Si-hydroxyl groups in the TEOS sol possess high activity, the silica gel can be easily adsorbed onto the surface of the Si nanoparticles. The as-synthesized Si-SiO composites yield a core-shell structure. Besides, the crystalline structure of the obtained SiO shell is highly... 

Microscale thermal transport phenomenon involves complex transfer mechanism of free electrons and phonons. The molecular dynamics and processes are not significant in most of the microscopic engineering applications. However, scale effects become extremely important in system with sudden high heat flux irradiation by laser pulses and some other dimensionally space- and time-governed problems. Anisimov etal. (1974) proposed the first two-step model for microscale conduction as... 

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