Josef Blair Simeonsson

US Patent:

20030059950, Mar 27, 2003

Filed:

Mar 11, 2002

Appl. No.:

10/096330

Inventors:

Josef Simeonsson - Durham NC, US

International Classification:

G01N033/00

US Classification:

436/182000, 436/073000, 436/181000, 436/164000, 436/172000, 423/644000, 422/082050, 422/082080, 422/083000

Abstract:

An analytical apparatus including a hydride generator coupled with a a laser-based detection device, with the generator suitable for generating hydrides from a sample, and the detection device positioned to receive hydrides from the hydride generator, and to provide information regarding quantity, identity, presence and/or species of the hydride. A method of processing a sample includes generating hydrides from the sample, and generating information regarding quantity, identity, presence and/or species of the hydride.

US Patent:

58660739, Feb 2, 1999

Filed:

Feb 28, 1997

Appl. No.:

8/808731

Inventors:

Rosario C. Sausa - Bel Air MD
Josef B. Simeonsson - Iowa City IA

Assignee:

The United States of America as represented by the Secretary of The Army - Washington DC

International Classification:

G01N 2101
G01N 2163

US Classification:

422 8205

Abstract:

A method and apparatus is provided for real-time detection of trace amounts of atmospheric and tropospheric halogen-containing compounds. The present invention can be used either for in situ detection or remote sensing. A laser is employed to induce photofragmentation of the halogenated molecules and facilitate detection of the characteristic atom fragment by stimulated emission spectrometry. For brominated compounds, the output of a single laser is tuned to the strong two-photon 4p. sup. 4 5p. sup. 4 D. degree. sub. 3/2. rarw. 4p. sup. 5 2 P. degree. sub. 3/2 transition of Br at 260. 634 nm. The Br atoms are subsequently detected by stimulated emission (SE) via the 4p. sup. 4 5p. sup. 4 D. degree. sub. 3/2. fwdarw. 4p. sup. 4 5s. sup. 4 P. sub. 5/2 transition at 844 nm. For comparison, the laser-induced fluorescence (LIF) signal at the same wavelength is also monitored.

US Patent:

57285845, Mar 17, 1998

Filed:

Sep 30, 1994

Appl. No.:

8/313620

Inventors:

Rosario C. Sausa - Bel Air MD
Josef B. Simeonsson - Iowa City IA
George W. Lemire - Draper UT

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01N 3322

US Classification:

436106

Abstract:

A method for the ultra-sensitive detection of atmospheric and surface adsorbed nitrocompounds such as propellants, explosives, and nitro-pollutants employs an excimer (ArF) laser operating at or near 193 nm to photofragment the target molecule and facilitate the detection of the characteristic NO fragment, formed from the dissociation of NO. sub. 2, by resonance-enhanced multiphoton ionization (REMPI) and/or laser induced fluorescence (LIF) via its A-X, B-X, C-X, and/or D-X electronic transitions. In addition to NO, the detection of other fragments, such as C, CH, C. sub. 2, NH and OH, by their ionization and/or prompt emission resulting from 193 nm excitation enhances the analyte identification. The analytical utility of this apparatus and method has been demonstrated on a number of compounds including dimethylnitramine (DMNA), nitromethane, nitrobenzene, orthonitrotoluene, para-nitrotoluene and trinitrotoluene (TNT). With the present system, limits of detection in the tens to hundreds of parts-per-billion (ppb) range have been achieved in the gas phase for all of these compounds, using only 1 mJ of laser energy at 193 nm.