TY - CONF A1 - Bierstedt, Andreas A1 - van Wasen, Sebastian A1 - Riedel, Jens T1 - Laser-spark ionization mass spectrometry N2 - A versatile ionization scheme for atmospheric pressure MS is presented. It is based on a quasi-continuous laser-induced plasma (LIP), generated by a 26 kHz pulsed DPSS-laser, which is ignited in front of the MS inlet. Analytes are determined with different sampling regimes, comprising either an ambient desorption/ionization mechanism, a liquid-phase or gas-phase sample introduction. The MS signal closely resembles the ionization behavior of APCI-like plasma-based sources, such as DBD or DART. Though LIPs are known to efficiently atomize/ionize any sample material, mass spectra of intact molecular ions are recorded, exhibiting low fragment-ion content. To understand this contradictory behavior, the plasma properties are investigated that lead to the formation of molecular ions. Comprehensive studies include optical emission spectroscopy, shadowgraph imaging and mass spectrometry diagnostics. The results show that the ionization of analyte does not occur in the plasma itself, but in the cold adjacent gas layer. The pulsed character of LIPs induces an expanding shockwave, which concentrically expands around the plasma core and sweeps the molecules toward the plasma edges, where they are ionized either directly by the self-emission of the hot core or via interaction with secondary reactants. However, this unidirectional transport causes a rarefaction inside the plasma center, which leads to a decrease in plasma intensity and number density. Thus, a restoration of the former gaseous medium by other dynamically equilibrated diffusion processes would be favorable. Besides gas replenishing, we demonstrate the beneficial use of an acoustical standing wave inside an ultrasonic resonator on the performance of the LIP. T2 - European Mass Spectrometry Conference 2018 CY - Saarbrücken, Germany DA - 11.03.2018 KW - Laser-spark ionization KW - Laser-induced plasma KW - Ambient mass spectrometry KW - DPSS laser PY - 2018 AN - OPUS4-44492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bierstedt, Andreas A1 - Bräkling, S. A1 - Rieger, J. A1 - Kersten, H. A1 - Glaus, Reto A1 - Gornushkin, Igor B. A1 - Riedel, Jens T1 - Development and characterization of an airborne laser-spark ion source for ambient desorption / ionization mass spectrometry N2 - A novel direct sampling ionization scheme for ambient mass spectrometry is presented. Desorption and ionization is achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. A laser plasma was ignited under ambient conditions in front of a modified TOF MS atmospheric pressure interface, using a high repetition rate DPSS laser operating at 532 nm and 26 kHz and an aspherical lens with a focal length of 8 mm. Emission spectroscopy (40-1100 nm) and time resolved studies on specific plasma parameters revealed insight into the physical and chemical plasma properties. Plasma ignition can be performed in rare gases and under ambient conditions. The hot plasma zone was kept at a certain distance from the sample region. Thus, effective collisional cooling seemed to prevent thermal fragmentation. Every single spark generates a shockwave, providing new reactive species, which expands concentrically from the hot region. Under ambient conditions primary charge carriers (ions and electrons) as well as VUV radiation initialize reaction cascades equivalent to other ambient ionization methods, such as DART or DBD. Mass spectra of polar/nonpolar hydrocarbons, sugars, pharmaceuticals and natural biomolecules in food were observed. Comprehensive emission spectroscopic measurements and time resolved electron current studies revealed insight into some plasma properties, such as the emitted high energetic radiation and the time evolution of the expanding plume. T2 - International Mass Spectrometry Conference 2016 CY - Toronto, ON, Canada DA - 20.08.2016 KW - laser-spark KW - laser-induced plasma KW - ambient mass spectrometry KW - emission spectroscopy PY - 2016 AN - OPUS4-37281 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bierstedt, Andreas A1 - Riedel, Jens A1 - Panne, Ulrich T1 - Elucidation of reagent-ion formation in a versatile low-temperature plasma probe combining emission spectroscopy and ambient time-of-flight mass spectrometry T2 - Berliner Chemie Symposium 2015 T2 - Berliner Chemie Symposium 2015 CY - Berlin, Germany DA - 2015-04-09 PY - 2015 AN - OPUS4-33638 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bierstedt, Andreas A1 - Panne, Ulrich A1 - Riedel, Jens T1 - Development of a new versatile instrument combining laser ablation mass spectrometry and laser emission spectroscopy T2 - 63rd ASMS Conference on Mass Spectrometry and Allied Topics T2 - 63rd ASMS Conference on Mass Spectrometry and Allied Topics CY - St. Louis, MO United States DA - 2015-05-31 PY - 2015 AN - OPUS4-33543 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bierstedt, Andreas A1 - Panne, Ulrich A1 - Riedel, Jens T1 - Charactization of a versatile low temperature plasma torch by optical emission spectroscopy and time-of-flight mass spectrometry T2 - DGMS 2015 T2 - DGMS 2015 CY - Wuppertal, Deutschland DA - 2015-03-01 PY - 2015 AN - OPUS4-33639 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bierstedt, Andreas A1 - Riedel, Jens T1 - Combination of Raman spectroscopy and laser ablation mass spectrometry T2 - Doktorandenseminar des DAAS -Spektroskopie und Spurenanalytik 2014 T2 - Doktorandenseminar des DAAS -Spektroskopie und Spurenanalytik 2014 CY - Münster, Germany DA - 2014-09-22 PY - 2014 AN - OPUS4-33641 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -