Laser desorption in an ion trap mass spectrometer

Laser desorption in a ion-trap mass spectrometer shows significant promise for both qualitative and trace analysis. Several aspects of this methodology are discussed in this work. We previously demonstrated the generation of both negative and positive ions by laser desorption directly within a quadrupole ion trap. In the present work, we explore various combinations of d.c., r.f., and time-varying fields in order to optimize laser generated signals. In addition, we report on the application of this method to analyze samples containing compounds such as amines, metal complexes, carbon clusters, and polynuclear aromatic hydrocarbons. In some cases the ability to rapidly switch between positive and negative ion modes provides sufficient specificity to distinguish different compounds of a mixture with a single stage of mass spectrometry. In other experiments, we combined intensity variation studies with tandem mass spectrometry experiments and positive and negative ion detection to further enhance specificity

Resonant laser ablation: Mechanisms and applications

We report on aspects of resonant laser ablation (RLA) behavior for a number of sample types: metals, alloys, thin films, zeolites and soil. The versatility of RLA is demonstrated, with results on a variety of samples and in several mass spectrometers. In addition, the application to depth profiling of thin films is described; absolute removal rates and detection limits are also displayed. A discussion of possible mechanisms for low-power ablation is presented

Molybdenum solar neutrino experiment

The goal of the molybdenum solar neutrino experiment is to deduce the /sup 8/B solar neutrino flux, averaged over the past several million years, from the concentration of /sup 98/Tc in a deeply buried molybdenum deposit. The experiment is important to an understanding of stellar processes because it will shed light on the reason for the discrepancy between theory and observation of the chlorine solar neutrino experiment. Possible reasons for the discrepancy may lie in the properties of neutrinos (neutrino oscillations or massive neutrinos) or in deficiencies of the standard solar model. The chlorine experiment only measures the /sup 8/B neutrino flux in current times and does not address possible temporal variations in the interior of the sun, which are also not considered in the standard model. In the molybdenum experiment, we plan to measure /sup 98/Tc (4.2 Myr), also produced by /sup 8/B neutrinos, and possibly /sup 97/Tc (2.6 Myr), produced by lower energy neutrinos

Analysis of surfaces, films and multilayers by resonant laser ablation

In this manuscript we review briefly the history of Resonant Laser Ablation (RLA), and discuss some current ideas regarding sample preparation, laser parameters, and mechanisms. We also discuss current applications including spectral analysis of trace components, depth profiling of thin films and multilayer structures, and the use of RLA with the Ion Trap Mass Spectrometer (ITMS)

Resonance ionization mass spectrometry for materials analysis and characterization

Resonance ionization mass spectroscopy (RIMS) is an analytical tool discovered in the 1970's, developed primarily in the 1980's, and one which will undoubtedly see continued and expanding use through the 1990's. This technique combines laser ionization with mass spectrometric sorting and detection to yield results of unparalleled sensitivity and selectivity. We discuss the application of RIMS to the analysis of conventional analytical samples, as well as the combinations of RIMS with laser or particle beam sputtering for the analysis of solids and surfaces with minimal sample preparation. 23 refs., 4 figs

Reaction of fluorine and chlorine atoms with formaldehyde and deutero-formaldehyde

The following reactions were studied by using infrared multiple photon dissociation to produce fluorine atoms, and infrared chemiluminescence to monitor the rate of reaction: Cl + H/sub 2/O ..-->.. HCl + HCO; F + H/sub 2/CO ..-->.. HF + HCO; Cl + D/sub 2/CO ..-->.. DCl + DCO; and F + D/sub 2/CO ..-->.. DF + DCO

Management of lamotrigine overdose using hemodialysis

© 2019 Elsevier Inc. Lamotrigine [LTG] is primarily an anti-epileptic drug used to treat seizure disorders, depression, and bipolar disease. It is generally well tolerated with limited side effects reported during routine use. Adverse events after overdose include neurotoxicity in the form of sedation and seizure activity, as well as cardiopulmonary toxicity in the form of sodium-channel blockade and cardiovascular collapse. There is no consensus regarding the role of hemodialysis (HD) in management of lamotrigine toxicity. Based on pharmacological properties, LTG is a candidate for extracorporeal removal, however, the successful use of HD for the treatment of this poisoning is not well described. We report the case of a 44 year-old female after a LTG overdose that experienced prolonged sedation that was ultimately treated with HD with an excellent response

Analytical capabilities of RIMS: absolute sensitivity and isotopic analysis. [Resonance ionization mass spectrometry]

The cw laser RIMS approach has been demonstrated to accurately measure large Lu isotope ratios and detect small levels of minor isotopes even in the presence of isobaric interferences. The same approach can also be used to obtain high resolution optical spectra of rare isotopes. For elements with higher ionization potentials (e.g., Tc), multicolor ionization schemes are necessary for cw RIMS measurements. Two-color RIMS spectra of Tc using pulsed lasers illustrate the feasibility of this approach. For any element, the sensitivity and selectivity of RIMS can be limited by the efficiency of ground state atom production in the sample volatilization step

Resonant multiphoton ionization for the detection of technetium

Experiments were carried out to determine optimum wavelengths for the selective ionization of technetium and to estimate the ultimate sensitivity obtainable for resonant ionization mass spectrometry detection of Tc in real samples. Results indicated that the 3099 and 3098 A lines may be analytically useful. The rate of ion production by laser excitation using pulsed lasers and techniques for volatilization of the sample are discussed. (MCG

Mass spectrometric studies of laser damage in calcium fluoride

Both electron impact- and laser-ionization-mass spectrometry have been used to prove the material spalled from CaF/sub 2/ surfaces by the fundamental (1.06..mu..) and harmonic (355 nm and 266 nm) outputs from a Q-switched Nd:YAG laser. We have identified a number of gas phase products, including Ca, CaF and tentatively, CaF/sub 2/, and have measured their translational and internal energy distributions. Results suggest that while the 1.06..mu.. experiments can be adequately modeled in terms of a single damage mechanism (likely avalanche breakdown), the short-wavelength results suggest the onset of second mechanism, perhaps multiphoton absorption. This is consistent with both the observed bimodal velocity distribution following short-wavelength damage, and with the decrease in CaF vibrational and rotational excitation