Infrared laser beams

Second-order NLO processes, including SFG, are strictly forbidden in media with inversion symmetry under the electric dipole approximation and are allowed only at the interface between these media where the inversion symmetry is necessarily broken. In the IR-Visible SFG measurement, a visible laser beam (covis) and a tunable infrared laser beam (cOir) are overlapped at an interface and the SFG signal is measured by scanning cOir while keeping cOvis constant. The SFG intensity (Isfg) is enhanced when coir becomes equal to the vibration levels of the molecules at the interface. Thus, one can obtain surface-specific vibrational spectra at an interface... 

Infrared diode laser spectroscopy has been used for the measurement of hydrocarbon and CO concentrations in exhaust (13, 14, 15). The adsorption path length, and thus the absorption cell volume, required for hydrocarbon measurement is rather large, limiting the time-resolution of the measurement. The absorption path length required for CO measurement, however, is relatively short and approximately equal to the diameter of a standard exhaust pipe. This allows CO to be measured with high time-resolution by an infrared laser beam passed through an... 

Ashkin, A. Dziedzic, J. M. Yamane, T., Optical trapping and manipulation of single cells using infrared laser beams, Nature 1987, 330, 769 771... 

This color-coded image shows a gold nanoparticle (dark red) heated with an infrared laser beam. The surroundings get hot as well, but the temperature fades quickly to 81 °F (27°C), represented by the color purple. (The color scale is given in Celsius.] [Yeonee Seol/JILA]... 

The use of a focused infrared laser beam on a surface results in local heating, which has been applied to synthesize MIPs locally by thermal polymerization [72]. In this case, a common thermo-initiator, azobisisobutyronitrile, was used together with a standard MIP recipe, to generate MIP microdots in a microfluidic device. 

The Nd-YAG infrared laser beam can be focused down to 10 pm, producing a microplasma from the sample and the carrier gas (Ar) that ablates the sample surface. The laser can be operated in two different modes with repetitive firing high magnification that produces a pit diameter of 20-40 pm, and low... 

Figure 11.46. (a) Recording of the 21,2 <— 17,1 vibration-rotation transition of the HD+ ion, obtained by Doppler tuning the ion beam into resonance with a carbon dioxide infrared laser beam [88], (b) A radiofrequency/infrared double resonance spectrum obtained by pumping the v3 line shown in the infrared spectrum (see text for the assignment). 

Figure 34.17. Watching a Single Motor Protein in Action. (A) An actin filament (blue) is placed above a heavy meromyosin (HMM) fragment (yellow) that projects from a bead on a glass slide. A bead attached to each end of the actin filament is held in an optical trap produced by a focused, intense infrared laser beam (orange). The position of these beads can be measured with nanometer precision. (B) Recording of the displacement of the actin filament induced by the addition of ATP. [After J. T. Finer, R. M. Simmons, and J. A. Spudich. Nature 368(1994) 113.]...

The feasibility of using infrared laser beams for the monitoring of phosgene in and around the plant has been described [ICI47-ICI49]. Phosgene has strong absorption bands at 849 (r ) and 1827 cm" (r,), but the combination band at 1011 cm" (r +rj), is less than one thirtieth of the intensity of the 1827 cm" band. The absorption data, appropriate to... 

Figure 6. Schematic view of the classical 90° angle HRS geometry. An intense infrared laser beam...

In contrast to the EFISH method, the hyperpolarizability P can be measured directly by means of the HRS method developed by Clays and Persoons [21, 22]. This method involves measuring the intensity of the incoherently scattered, frequency-doubled light from isotropic solutions. As shown in Fig. 3.2, an infrared laser beam is focused on the center of a cell containing a solution of the NLO-active compound. 

Fig. 2 Schematic diagram of laser optical tweezers (LOT) system. (Top panel) An infrared laser beam was steered to trap and move pm-size particles in the focal plane. At a sufficiently large laser intensity, the gradient force dominates over the scattering force. (Lower panel) Membrane tethers are extracted from live cells. Dielectric beads (0.5 pm in diameter) were conjugated with antibodies against integiins and attached to the cell membrane. LOT traps one bead and pulls it away from the cell, as indicated by the arrow. Thin membrane tethers extending from the beads to the cell body appear. Using conventional brightfield microscopy, the tether length and its diameter are measured which, in turn, provide an estimate of the plasma membrane tension.

D. Maydan, H. Melchior and F. Kahn, Liquid Crystal Graphic Displays Thermally Addressed by Infrared Laser Beams, IEEE Conference Record of 1972 Conference on Display Devices,... 

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