Search

Most ambient sample introduction and ionization techniques for native mass spectrometry are highly selective for polar agents. To achieve a more general sensitivity for a wider range of target analytes, a novel laser ablation dielectric barrier discharge (LA DBD) ionization scheme was developed. The approach employs a two-step mechanism with subsequent sample desorption and post-ionization. Effective ablation was achieved by the second harmonic output ( λ = 532 nm) of a diode pumped Nd:YVO 4 laser operating at a high-repetition rate of several kHz and pulse energies below 100 μJ. The ejected analyte-containing aerosol was consecutively vaporized and ionized in the afterglow of a DBD plasma jet. Depending on their proton affinity the superexcited helium species in this afterglow produced analyte ions as protonated and ammoniated species, as well as radical cations. The optimization procedure could corroborate underlying conceptual consideration on the ablation, desorption and ionization mechanisms. A successful detection of a variety of target molecules could be shown from the pharmaceutical ibuprofen, urea, the amino acids l -arginine, l -lysine, the polymer polyethylene glycol, the organometallic compound ferrocene and the technical mixture wild mint oil. For a reliable evaluation of the introduced detection procedure spectra from the naturally abundant alkaloid capsaicin in dried capsicum fruits were recorded. [ABSTRACT FROM AUTHOR]

At the Kansai Photon Science Institute (KPSI, Kyoto, Japan), there are three unique high-power laser facilities. Here, we introduce the features of each facility and some experimental studies, which will be useful to users as a reference.

Laser irradiation of dispensed tungsten powder layers with grain sizes smaller than 1 μm was investigated using high-repetition femtosecond laser systems. Laser processing was performed line by line with repetition rates up to 1 MHz and varying parameters such as laser power, processing speed, number of scans and pressure. In addition to the expected material ablation and melting, nov-el phenomena such as crystallisation, emergence of ripple structures, extensive agglomeration and the formation of nano-wires will be discussed qualitatively with the help of SEM photographs. De-pendence on light pressure, pulse overlap and irradiated energy per unit length will be demonstrated. High-resolution microstructures will be discussed as a first application of innovative laser microsin-tering technology using high-repetition femtosecond laser pulses. [ABSTRACT FROM AUTHOR]