= Michael Karas
{c}
\b[Michael Karas] is a researcher associated with the experimental development of <MALDI> <mass spectrometry>. His 1985 paper with collaborators examined how laser <wavelength> and sample absorption influence ion formation from organic solids. The paper lists an affiliation with the Institute of Biophysics at the University of Frankfurt.<Influence of the Wavelength in High-Irradiance Ultraviolet Laser Desorption Mass Spectrometry of Organic Molecules by Michael Karas and others>[p2935, author byline, affiliation and Abstract]{ref}
A central experiment mixed <alanine> with <tryptophan>, which absorbs at 266 nm. At that wavelength, the mixture yielded an alanine-related ion at about one tenth of the <irradiance> required for spectra of alanine alone. The absorbing matrix therefore changed the conditions under which the other component could be observed, rather than merely adding its own peak to the spectrum.<Influence of the Wavelength in High-Irradiance Ultraviolet Laser Desorption Mass Spectrometry of Organic Molecules by Michael Karas and others>[p2937, Figure5 and Matrix-Assisted Laser Desorption]{ref}
An original pulse-accounting example shows why the measurement conditions matter. If a uniform pulse has irradiance $I=10^7\,\mathrm{W\,cm^{-2}}$ for $\tau=10\,\mathrm{ns}$, its <radiant exposure> is
$$
H=I\tau=0.1\,\mathrm{J\,cm^{-2}}.
$$
At the same irradiance, a one-nanosecond pulse gives $0.01\,\mathrm{J\,cm^{-2}}$. These chosen values are not the experimental thresholds. Equal irradiance does not imply equal deposited energy per area when pulse duration differs.
The original study discussed competing mechanisms for the observed wavelength and matrix effects rather than establishing one universal ionization pathway.<Influence of the Wavelength in High-Irradiance Ultraviolet Laser Desorption Mass Spectrometry of Organic Molecules by Michael Karas and others>[Discussion]{ref} That combination of controlled comparison and mechanistic alternatives makes the work scientifically informative beyond a single improved signal. A university https://campus.uni-muenster.de/fileadmin/einrichtung/alumninetz/Community_Newsletter_1_2010_22-07-2010.pdf[newsletter with a portrait and development-era apparatus photograph] provides a primary visual reference.
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