Multiphoton microscopy is becoming a popular mode of live and fixed cell imaging. This mode of imaging offers several advantages due to the fact that fluorochrome excitation is a nonlinear event resulting in excitation only at the plane of focus. Multiphoton excitation is enhanced by the use of ultrafast lasers emitting in the near IR, offering better depth penetration coupled with efficient ex...

The effect of laser line shape and bandwidth on the signal detected in two-color, resonant four-wave mixing ~TC-RFWM! spectroscopy is determined by means of an ab initio calculation of the third-order polarization based on diagrammatic perturbation theory. Modifications to the approach previously used for the case of d-function laser line shapes are made by introducing a different treatment of ...

The vibrational excitation of a tubular M13 bacteriophage capsid is simulated using classical molecular dynamics. The excitation occurs through impulsive stimulated Raman scattering by ultra-short laser pulses which ping the vibrational modes of the capsid. Tuning the laser pulse temporal width determines the frequency region of the capsid that is excited. The simulations reveal that electromag...

BACKGROUND AND OBJECTIVE Photodynamic therapy (PDT) treats malignant tumors using photosensitizers and light. We employed a new pulse laser as the excitation light source for PDT, i.e. an optical parametric oscillator (OPO) system pumped by a Q-switched Nd:YAG laser, because it provides extremely high peak power. STUDY DESIGN/MATERIALS AND METHODS The effects of PDT using the photosensitizer ...

We report the use of an all-solid-state ultrashort pulsed source specifically for two-photon microscopy at wavelengths shorter than those of the conventional Ti:Sapphire laser. Our approach involves sum-frequency mixing of the output from an optical parametric oscillator (λ= 1400-1640 nm) synchronously pumped by a Yb-doped fibre laser (λ= 1064 nm), with the residual pump radiation. This generat...

A laser-pump, x-ray probe spectroscopic experiment is described, and the results are shown. The Ga Ka x-ray fluorescence following x-ray absorption, at the Ga K absorption edge was measured, and its increase due to excitation with subpicosecond pulses of laser light at 4.6 eV photon energy was determined. The x-ray absorption, and thus the fluorescence, is increased for about 200 ps after the l...

Single and multi-mode room temperature laser action was observed in GaN pyramids under strong optical pumping. The 5and 15-micron-wide hexagonal-based pyramids were laterally overgrown on a patterned GaN/AlN seeding layer grown on a (111) silicon substrate by metal-organic chemical vapor deposition. The pyramids were individually pumped, imaged, and spectrally analyzed through a high magnificat...

Phase transformations of InSb~211! induced by 130-fs laser pulses at 800 nm have been time resolved in a wide range of laser fluences. The pump-probe technique has been used, where both optical reflectivity and reflected second-harmonic generation ~SHG! from the probe pulses are monitored as functions of probe versus pump pulse delay. The results are indicative of InSb undergoing a phase transi...

The temporal resolution of a two-photon excitation laser scanning microscopy (TPLSM) system is limited by the excitation laser beam's scanning speed. To improve the temporal resolution, the TPLSM system is equipped with a spinning-disk confocal scanning unit. However, the insufficient energy of a conventional Ti:sapphire laser source restricts the field of view (FOV) for TPLSM images to a narro...

Polarized surface-enhanced Raman scattering (SERS) spectroscopy was applied for obtaining biochemical information about the seminal plasma. The effect of different laser polarizations (nonpolarized, linear-polarized, right-handed circularly polarized, and left-handed circularly polarized) on seminal plasma SERS spectroscopy was explored for the first time. The diagnostic performance in differen...