Development and characterization of a laser-induced acoustic desorption source

A laser-induced acoustic desorption source, developed for use at central facilities, such as free-electron lasers, is presented. It features prolonged measurement times and a fixed interaction point. A novel sample deposition method using aerosol spraying provides a uniform sample coverage and hence stable signal intensity. Utilizing strong-field ionization as a universal detection scheme, the produced molecular plume is characterized in terms of number density, spatial extend, fragmentation, temporal distribution, translational velocity, and translational temperature. The effect of desorption laser intensity on these plume properties is evaluated. While translational velocity is invariant for different desorption laser intensities, pointing to a non-thermal desorption mechanism, the translational temperature increases significantly and higher fragmentation is observed with increased desorption laser fluence.Comment: 8 pages, 7 figure

Laser-induced acoustic desorption of large molecules via tape-drive method

By dispersing molecular beams with strong electric fields, we can routinely produce pure samples of individual conformers or clusters according to their quantum state. Selected molecules can be further controlled using alignment and orientation by laser and static electric fields [1]. We are currently working towards extending these techniques to much large molecules and systems. Laser-induced acoustic desorption (LIAD) is a promising technique for gentle and efficient preparation of large intact neutral molecules in the gas-phase [2]. Here we demonstrate our newly set-up LIAD source, designed for prolonged measurement times through automatic sample replenishment. Molecules are sprayed onto a long 10 µ m tantalum foil band that is irradiated from the backside by a third harmonic Nd:YAG laser (355 nm). The induced shockwave travels through the foil and desorbs molecules from the frontside of the foil. We present results and characterizations of the source, and discuss its potential for applications in x-ray or electron diffraction imaging. [1] Y. P. Chang, D. A. Horke, S. Trippel and J. Küpper, Int. Rev. Phys Chem. 34, 557 (2015); [2] B. Lindner and U. Seydel, Anal. Chem. 57, 895 (1985)

Laser-induced acoustic desorption of large molecules for FEL experiments

Laser-induced acoustic desorption (LIAD) is a promising technique for gentle and efficient preparation of large intact neutral molecules into the gas-phase [1]. Here we demonstrate our newly set-up LIAD source, designed for prolonged measurement time, as required by FEL experiments, through automatic sample replenishment. Using a gas dynamic virtual nozzle we deposit a near-uniform layer of sample on a ∼1 m long, 10 µm thick tantalum foil band. An acoustic wave was initiated by irradiating the backside of the foil with the third harmonic of a nanosecond Nd:YAG laser. The induced photoacoustic shock wave travels through the foil and desorbs samples into the gas-phase. A stable neutral phenylalanine plume was prepared and characterized using strong-field ionization by an intense femtosecond laser field with a linear time of flight mass spectrometer. Spatial-temporal profiles, velocity distributions of the LIAD plume as a function of desorption laser intensity were investigated. Its potential for applications in x-ray or electron diffraction imaging will be discussed. [1] B. Lindner and U. Seydel, Anal. Chem. 57, 895 (1985)

Comparison of classical and modern forms of electrodiagnosis of peripheral pareses

Tato práce je zaměřena na vyšetření periferních paréz elektrodiagnostickými metodami. Metody rozdělujeme na klasické a moderní. Klasické a moderní metody elektrodiagnostiky byly porovnávány na 2 pacientech postižených periferní parézou. Pacienti byli vyšetřeni svalovým testem, neurologickým vyšetřením a elektrodiagnostickými metodami.Katedra fyzioterapie a ergoterapieObhájenoThis bachelor work is focused on electrodiagnostic screening of peripheral pareses. Electrodiagnostic methods are divided into modern and classical. Two disabled patients suffering from peripheral pareses have been compared by the means of these methods. The patients have been examined with the use of the muscle test, neurological and electrodiagnostic examination