Laser pulse energy

Based on the principle of the Raman microscope, a regular transmission and reflex ion optical microscope has been modified to unable tunable pulsed laser injection as well as fluorescence collecting via an optic fiber up to a intensified CCD camera allowing time resolved records. For this purpose, aU optics was replaced to support high-energy laser pulses. Such equipment allows the following (Panczer et al. 2003) ... 

Figure 12.29. Photographs of the exit plane of the fiber array before, right after, and a few minutes after the high energy laser pulse. During live imagery, we observed a large bubble float out of the sample test region.

After cell handling and cell characterization, a lab-on-a-cell system requires the access to the intracellular content, via crossing the cell membrane, which can be performed by an electric field, pore-inducing chemicals, or high-energy laser pulses (Wang et al., 2010 Olofsson et al., 2009). Fig. 12.2 presents an example of a lab-on-a-cell microfluidic device (Clausell-Tormos et al., 2008). 

SFIG or SFG from a medium that has a strong response in a separate detection anu. By this means, one may fiilly compensate for variations not only in pulse energy, but also in the temporal and spatial substructure of the laser pulses. Some experiments may require measurement of the phase of the nonlinear signal [57]. 

The most connnon commercially prepared amplifier systems are pumped by frequency-doubled Nd-YAG or Nd-YLF lasers at a 1-5 kHz repetition rate a continuously pumped amplifier that operates typically in the 250 kHz regime has been described and implemented connnercially [40]. The average power of all of the connnonly used types of Ti-sapphire amplifier systems approaches 1 W, so the energy per pulse required for an experiment effectively detennines the repetition rate. 

Figure B2.5.11. Schematic set-up of laser-flash photolysis for detecting reaction products with uncertainty-limited energy and time resolution. The excitation CO2 laser pulse LP (broken line) enters the cell from the left, the tunable cw laser beam CW-L (frill line) from the right. A filter cell FZ protects the detector D, which detennines the time-dependent absorbance, from scattered CO2 laser light. The pyroelectric detector PY measures the energy of the CO2 laser pulse and the photon drag detector PD its temporal profile. A complete description can be found in [109].

J and Vrepresent the rotational angular momentum quantum number and tire velocity of tire CO2, respectively. The hot, excited CgFg donor can be produced via absorjDtion of a 248 nm excimer-laser pulse followed by rapid internal conversion of electronic energy to vibrational energy as described above. Note tliat tire result of this collision is to... 

CgFg molecules (CgFg - ) are produced at energy E = A 822 cnA by an excimer laser pulse (25 ns). 

Seilmeier A and Kaiser W 1988 Ultrashort intramoleoular and intermoleoular vibrational energy transfer of polyatomio moleoules in liquids Ultrashort Laser Pulses and Applications (Topics in Applied Physics 60) ed W Kaiser (Berlin Springer) pp 279-315... 

A laser pulse strikes the surface of a sample (a), depositing energy, which leads to melting and vaporization of neutral molecules and ions from a small, confined area (b). A few nanoseconds after the pulse, the vaporized material is either pumped away or, if it is ionic, it is drawn into the analyzer of a mass spectrometer (c). 

Much of the energy deposited in a sample by a laser pulse or beam ablates as neutral material and not ions. Ordinarily, the neutral substances are simply pumped away, and the ions are analyzed by the mass spectrometer. To increase the number of ions formed, there is often a second ion source to produce ions from the neutral materials, thereby enhancing the total ion yield. This secondary or additional mode of ionization can be effected by electrons (electron ionization, El), reagent gases (chemical ionization. Cl), a plasma torch, or even a second laser pulse. The additional ionization is often organized as a pulse (electrons, reagent gas, or laser) that follows very shortly after the... 

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