Mass spectrometers such as SELDI-TOF (surface enhanced laser desorption/ionization time-of-flight) and MALDI-TOF (matrix assisted laser desorption and ionization time-of-flight) measure the relative abundance of different protein ions or protein fragments (peptides) indexed by the mass-to-charge ratio (m/z). A special characteristic of the MS spectra is its variabilities in both m/z values and ...

A time-of-flight mass spectrometer (TOF-MS) developed in our laboratory at Isfahan University of Technology is described here. The TOF-MS instrument uses laser as the ionization source which provides an opportunity to investigate the ions formed in laser ablation or desorption. The TOF-MS has an ionization chamber containing an accelerator and an ion lens to focus the ions into a one meter line...

We study resonant two-photon ionization of helium atoms via the 1 s 3 p , 4 and 5 P states using 15 th harmonic a titanium-sapphire laser for excitation weak fraction field ionization. The phase photoelectron wavepackets is measured by an attosecond interferometric technique, 17 harmonic. perform experiments with angular resolution velocity map imaging spectrometer high energy magnetic bottle e...

Ionization processes limit the accelerating gradient and place an upper limit on the pulse duration of the electromagnetic driver in the inverse Cherenkov accelerator ~ICA!. Group velocity slippage, i.e., pulse lethargy, on the other hand, imposes a lower limit on the pulse duration. These limits are obtained for two ICA configurations in which the electromagnetic driver ~e.g., laser or millime...

The propagation of short, intense laser pulses in the atmosphere is investigated theoretically and numerically. A set of three-dimensional (3D), nonlinear propagation equations is derived, which includes the effects of dispersion, nonlinear self-focusing, stimulated molecular Raman scattering, multiphoton and tunneling ionization, energy depletion due to ionization, relativistic focusing, and p...