LAMMA

In Laser Ionization Mass Spectrometry (LIMS, also LAMMA, LAMMS, and LIMA), a vacuum-compatible solid sample is irradiated with short pulses ("10 ns) of ultraviolet laser light. The laser pulse vaporizes a microvolume of material, and a fraction of the vaporized species are ionized and accelerated into a time-of-flight mass spectrometer which measures the signal intensity of the mass-separated ions. The instrument acquires a complete mass spectrum, typically covering the range 0— 250 atomic mass units (amu), with each laser pulse. A survey analysis of the material is performed in this way. The relative intensities of the signals can be converted to concentrations with the use of appropriate standards, and quantitative or semi-quantitative analyses are possible with the use of such standards. 

A somewhat related technique is that of laser ionization mass spectrometry (LIMS), also known as LIMA and LAMMA, where a single pulsed laser beam ablates material and simultaneously causes some ionization, analogous to samples beyond the outer surface and therefore is more of a bulk analysis technique it also has severe quantiBaction problems, often even more extreme than for SIMS. 

LAMMA Laser microprobe mass analysis (see LRRS Low-resolution Raman spectroscopy... 

The technique is referred to by several acronyms including LAMMA (Laser Microprobe Mass Analysis), LIMA (Laser Ionisation Mass Analysis), and LIMS (Laser Ionisation Mass Spectrometry). It provides a sensitive elemental and/or molecular detection capability which can be used for materials such as semiconductor devices, integrated optical components, alloys, ceramic composites as well as biological materials. The unique microanalytical capabilities that the technique provides in comparison with SIMS, AES and EPMA are that it provides a rapid, sensitive, elemental survey microanalysis, that it is able to analyse electrically insulating materials and that it has the potential for providing molecular or chemical bonding information from the analytical volume. 

Odom and Schueler (1990) describe the basic components of the instrument, known as LIMA 2A or LAMMA 1000, depending upon the particular manufacturer. Figure 3.11 illustrates a schematic diagram of a reflection mode instrument. 

Infrared and ultraviolet probes for surface analysis are then considered.The applications of IR spectroscopy and Raman microscopy are discussed, and a brief account is also given of laser-microprobe mass spectrometry (LAMMA). 

The primary methods of analyzing for lead in environmental samples are AAS, GFAAS, ASV, ICP/AES, and XRFS (Lima et al. 1995). Less commonly employed techniques include ICP/MS, gas chromato-graphy/photoionization detector (GC/PID), IDMS, DPASV, electron probe X-ray microanalysis (EPXMA), and laser microprobe mass analysis (LAMMA). The use of ICP/MS will become more routine in the future because of the sensitivity and specificity of the technique. ICP/MS is generally 3 orders of magnitude more sensitive than ICP/AES (Al-Rashdan et al. 1991). Chromatography (GC,... 

The origin of lead present in individual calcite particles could be ascribed by the LAMMA (laser microprobe mass analysis) technique. At low laser irradiances, the desorption mode, information is gathered on metallic species adsorbed on the surface of the particle. At high irradiances the particle is evaporated, revealing the components that coprecipitated with calcite111. 

There are now several different types of machines that are all capable of microanalysis. All have advantages and disadvantages, but the choice of which to use is often governed by expense and availability to a particular institution. Electron probe microanalysis is by far the most popular, but here particle-induced X-ray emission (PIXE), the laser microprobe mass analyzer (LAMMA), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) are also considered. 

Of all of the machines used for microanalysis LAMMA seems to be the most problematic. A laser beam is used to disintegrate a spot in the sample, and the material emitted is then analyzed in a mass spectrometer. It has similar lateral resolution to PIXE, and like SIMS can be used to distinguish between isotopes of the same element. It has, however, proved very difficult to quantify, and is destructive to the specimen. One recent investigation (13) ofthe distribution of stable isotopes of calcium, magnesium, and potassium in Norway spruce used three microprobes EDAX at 0.3 pm lateral resolution isotope specific point analysis, using LAMMA at 1.5 pm lateral resolution and isotope specific imaging using SIMS at 1-3 pm lateral resolution. 

Lammas DA, Drysdale P. Calvert JE. Cant AJ, Abinun M Deregulated production of protective cytokines in response to Candida albicans infection in patients with chronic mucocutaneous candidiasis. Infect Immun 2003 71 5690-5699. 

Altare, R, Durandy, A., Lammas, D., et al, Impairment of mycobacterial immunity in human interleukin-12 receptor deficiency. Science 280, 1432-1435 (1998). 

Altare, F., Lammas, D., Revy, R, etal, Inherited interleukin-12 deficiency in a child with bacille Calmette-Guerin and salmonella enteritidis disseminated infection. J. Clin. Invest. 102, 2035-2040 (1998). 

Kaufmann, R. L., Laser Microprobe Mass Spectroscopy (LAMMA) of Particulates, in Physical and Chemical Characterization of Individual Airborne Particles (K. R. Spurny, Ed.), Chap. 13, pp. 227-250, Ellis Horwood, Chichester, 1986. 

The development of laser ionization mass spectrometry was started by Honig and Woolston in 196359 with studies of laser beam sohd surface interaction and ion formation processes. Due to the pulse character of laser-induced ions, ToF analyzers were coupled to laser ion sources in the seventies and produced commercially as LAMMA-500 and later LAMMA-1000 and 2000 (Leybold-Heraeus, Cologne, Germany). 

In the past, for the analysis of thin sections of tissues or thin transparent foils a laser ionization ion source in the transmission or reflection mode of laser irradiation (using e.g., the LAMMA 500 or LAMMA 1000, respectively) was employed. The lateral resolution observed in the transmission mode was about 1 (im and in the reflection mode 5-20 gm. 

Figure 5.25 Schematic arrangement of the LAMMA-500 with time-of-flight analyzer and reflectron using the transmission mode. (J. S. Becker and H. J. Dietze, Fresenius. j. Anal. Chem. 344, 69 (/992). Produced by permission of Springer Sciences and Business Media.)...

In general, in ICP-MS, metal argide ions (MAr+) are observed at lower intensities compared to the dimeric metal oxide ions (MO+). Both ionic species correlate with the bond dissociation energies in the ICP or by the expansion of plasma in the vacuum. A correlation of measured oxide ion intensities (MO+) and experimentally determined or theoretically calculated bond dissociation energies of oxides has been found in laser mass spectra using a LAMMA 500 (laser microprobe mass analyzer, Leybold Hereaus AG, Cologne) by Michiels and Gijbels.52... 

Lammas, D.A. and Duffus, W.P. (1983) The shedding of the outer glycocalyx of juvenile Fasciola hepatica. Veterinary Parasitology 12, 1 65-1 78. 

Laser beams can be focused down to the diffraction limit of 0.2 -0.5 Vim with very high efficiency. This has lead to the development of thg Laser-Mass-Spectrometric Microprobes LAMMA 500, ... 

LAMMA 1000 and LIMA. These instruments are designed for tasks in principle comparable to those of dynamic SIMS or imaging ion-microprobes. ... 

This paper contains a discussion of the most important features of laser-induced-ion spectra and mechanisms of ion formation, some of them experimentally proven, some of them still under discussion and investigation. Special attention will be given to the LAMMA technique, because this is the authors own field of work, but reference to other systems will be included where appropriate. 

For the techniques using very short, high irradiance laser pulses, a more or less smooth transition to pyrolysis of the sample is observed with increasing irradiance. It appears that at least for the LAMMA technique this transition does not always occur at identical irradiances for positive and negative ions. This will be discussed in more detail later in this paper. 

The term desorption is used in contrast to evaporation in cases in which a transition of a molecular or ion from the condensed into the gas phase is assumed to take place under non thermal equilibrium condition. The underlying idea is that at thermal equilibrium, temperatures for an evaporation would lead to a correspondingly high excitation of internal vibrational modes of excitation leading to fraigmentation of the molecule. As mentioned above, several characteristics of the ion spectra (2., 6.) cannot reasonably be fitted to an equilibrium temperature model. These properties seem to be the more pronounced, the higher the laser irradiance (i.e. usually the shorter the pulse) and are best documented for the LAMMA technique. Though metastable decay of ions is observed and will be discussed below, the decay rate for most of the ions is very small and decay... 

Figure 2. Schematic diagram of LAMMA 500 instrument, adapted for simultaneous detection of ions and neutrals.

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