Spectroscopy - June 2009 - (Page 34) 34 Spectroscopy 24(6) June 2009 w w w. s p e c t r o s c o p y o n l i n e . c o m combined double-laser pulse is directed along the axis of the telescope by an articulating arm, enabling a full range of motion on the telescope for ease in targeting the sample. A diode laser (632 nm) illuminates the target spot coincident with the main IR laser. The infrared double-pulse beam is expanded with a simple two-lens system and is focused down range by a 3 positive lens (f = 475 mm). Plasma light collected by the telescope is focused into a fiber optic and sent to a gated CCD spectrometer (500–900 nm) developed by Ocean Optics. A digital camera and wireless range finder enable remote viewing and measurement of the distance to the target. Although we were able to collect spectra of metals and explosive residues on metals at 20 m with the Gen 1 system, we found that the less-than-ideal beam quality of the lasers in the far-field resulted in a weaker plasma that made obtaining LIBS spectra of organic materials extremely challenging. For the Gen 2 system, therefore, a double-pulse laser source (Quantel Brilliant Twins, 1064 nm, 10 Hz, 335 mJ/ pulse, 5 ns pulse width) that provided superior beam quality (M2 < 2) and power at 20+ m was selected. As with the Gen 1 system, the two laser beams are combined before entering the articulating arm. A 14 telescope (Meade LX200GPS) was fitted with UV-coated optics to provide greater light-gathering power compared with Gen 1 and full broadband (UV–vis–NIR) capability. A custommade three-channel gated CCD spectrometer (Ocean Optics) provides high light throughput and sensitivity from 190 nm to 840 nm. The entire system is mounted on a wheeled cart and is easily transportable. The data presented in the following section were acquired using the Gen 2 system (pictured in Figure 1). The optimal timing parameters for the system are as follows: delay time tdelay = 2 s, integration time gate tint = 100 s, and interpulse separation t = 3 s. A third-generation standoff LIBS system has been designed to address the issue of eye safety. A single Nd:YAG laser (Quantel Brilliant B, 1064 nm, 10 Hz, 850 mJ, 6 ns pulse width) is shifted to 1.54 m using a CH4/Ar-filled Raman cell developed by the National Center for Y predicted (RDX class) Model index number Test sample index number Figure 3: PLS-DA results for unknown residues on red silicone substrate tested against the RDX class of the model: RDX = blue square, dust = rust circle, oil = black diamond, and red substrate (blank) = red triangle. The open shapes are the sample spectra in the model and the filled shapes are the “unknown” test samples. The dashed line is the threshold for determining if a test sample belongs to the RDX class. (a) Intensity (arbitrary units) (b) (c) Wavelength (nm) Figure 4: Standoff LIBS spectra of biomaterials collected at 40 m: (a) Broadband spectra of BG in G (blue) and BG in SpBr (red); (b) close-up view of BG in G (blue) and BG in SpBr (red) to compare differences in growth media; and (c) close-up view of BG in SpBr (red) and Bt in SpBr (black) to compare differences in spore type Atmospheric Research (NCAR). As with the Gen 2 system, a modified 14 telescope is used to collect the light emitted from the laser-induced plasma. Testing of this system is under way, but this system will be used primarily as a proof-ofconcept due to power limitations at 1.54 m. The high laser energies necessary for these standoff systems will always be unsafe in the beam path, regardless of wavelength. However, potential damage from reflections and scatter can be mitigated by using wavelengths such as 1.54 m or the third and fourth harmonics of the Nd:YAG rather than the fundamental and second harmonic of the Nd: YAG. Therefore, the area around the standoff system that must be controlled http://www.spectroscopyonline.com Table of Contents for the Digital Edition of Spectroscopy - June 2009 Spectroscopy - June 2009 Contents News Spectrum Auger Spectroscopy Statistics and Chemometrics for Clinical Data Reporting, Part 1 Understanding and Interpreting the New GAMP 5 Software Categories Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels Product Resources Calendar Ad Index Spectroscopy - June 2009 Spectroscopy - June 2009 - (Page BB1) Spectroscopy - June 2009 - (Page BB2) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page Cover1) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page Cover2) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page 3) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page 4) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page 5) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page 6) Spectroscopy - June 2009 - Spectroscopy - June 2009 (Page 7) Spectroscopy - June 2009 - Contents (Page 8) Spectroscopy - June 2009 - Contents (Page 9) Spectroscopy - June 2009 - Contents (Page 10) Spectroscopy - June 2009 - Contents (Page 11) Spectroscopy - June 2009 - News Spectrum (Page 12) Spectroscopy - June 2009 - News Spectrum (Page 13) Spectroscopy - June 2009 - Auger Spectroscopy (Page 14) Spectroscopy - June 2009 - Auger Spectroscopy (Page 15) Spectroscopy - June 2009 - Auger Spectroscopy (Page 16) Spectroscopy - June 2009 - Auger Spectroscopy (Page 17) Spectroscopy - June 2009 - Statistics and Chemometrics for Clinical Data Reporting, Part 1 (Page 18) Spectroscopy - June 2009 - Statistics and Chemometrics for Clinical Data Reporting, Part 1 (Page 19) Spectroscopy - June 2009 - Statistics and Chemometrics for Clinical Data Reporting, Part 1 (Page 20) Spectroscopy - June 2009 - Statistics and Chemometrics for Clinical Data Reporting, Part 1 (Page 21) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 22) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 23) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 24) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 25) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 26) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 27) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 28) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 29) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 30) Spectroscopy - June 2009 - Understanding and Interpreting the New GAMP 5 Software Categories (Page 31) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 32) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 33) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 34) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 35) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 36) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 37) Spectroscopy - June 2009 - Current Status of Standoff LIBS Security Applications at the United States Army Research Laboratory (Page 38) Spectroscopy - June 2009 - Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels (Page 39) Spectroscopy - June 2009 - Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels (Page 40) Spectroscopy - June 2009 - Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels (Page 41) Spectroscopy - June 2009 - Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels (Page 42) Spectroscopy - June 2009 - Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels (Page 43) Spectroscopy - June 2009 - Spectral Studies on the Interaction of [Ru(bpy)2(BTIP)]2+ with DNA and Determination of Nucleic Acids at Nanogram Levels (Page 44) Spectroscopy - June 2009 - Product Resources (Page 45) Spectroscopy - June 2009 - Product Resources (Page 46) Spectroscopy - June 2009 - Product Resources (Page 47) Spectroscopy - June 2009 - Calendar (Page 48) Spectroscopy - 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