John R. Quagliano

Quantitative chemical identification of four gases in remote infrared (9–11 µm) differential absorption lidar experiments

A combined experimental and computational approach utilizing tunable CO(2) lasers and chemometric analysis was employed to detect chemicals and their concentrations in the field under controlled release conditions. We collected absorption spectra for four organic gases in the laboratory by lasing 40 lines of the laser in the 9.3-10.8-mum range. The ability to predict properly the chemicals and their respective concentrations depends on the nature of the target, the atmospheric conditions, and the round-trip distance. In 39 of the 45 field experiments, the identities of the released chemicals were identified correctly without predictions of false positives or false negatives.

Operator declaration verification technique for spent fuel at reprocessing facilities

Abstract A verification technique for use at reprocessing facilities, which integrates existing technologies to strengthen safeguards through the use of environmental monitoring, has been developed at Los Alamos National Laboratory. This technique involves the measurement of isotopic ratios of stable noble fission gases from on-stack emissions during reprocessing of spent fuel using high-precision mass spectrometry. These results are then compared to a database of calculated isotopic ratios using a data analysis method to determine specific fuel parameters (e.g., burnup, fuel type, reactor type, etc.). These inferred parameters can be used to verify operator declarations. The integrated system (mass spectrometry, reactor modeling, and data analysis) has been validated using on-stack measurements during reprocessing of fuel from a US production reactor. These measurements led to an inferred burnup that matched the declared burnup to within 3.9%, suggesting that the current system is sufficient for most safeguards applications. Partial system validation using gas samples from literature measurements of power reactor fuel has been reported elsewhere. This has shown that the technique developed here may have some difficulty distinguishing pressurized water reactor (PWR) from boiling water reactor (BWR) fuel; however, it consistently can distinguish light water reactor (either PWR or BWR) fuels from other reactor fuel types. Future validations will include advanced power reactor fuels (such as breeder reactor fuels) and research reactor fuels as samples become available.

Optical Characterization and Electronic Energy-Level Structure of Er3+-Doped Cscdbr3

Information obtained from optical absorption, excitation, and emission experiments on erbium doped crystalline CsCdBr3 is analyzed, using a semiempirical Hamiltonian, to calculate atomic and crystal‐field interaction parameters and electronic state wave functions. A majority of the Er3+ ions substitute at a Cd2+ site giving C3v point group symmetry and forming an Er3+ ion dimer center. This dimerization, together with the material’s low phonon energies, and the specific positioning of states in the Er3+ (4f11) configuration, produce the interesting and useful emission properties of the material. Comparisons are made with other erbium halide crystals, and interaction parameter and energy‐level results for Nd3+:CsCdBr3 are also presented. The inclusion of second order correlation crystal‐field interaction parameters is shown to be essential for accurately characterizing splittings of several J multiplets important in visible emission pathways.

Electronic energy‐level structure and correlation crystal‐field effects of Er3+ in Cs3Lu2Br9

Single crystals of Cs3Lu2Br9:1% Er3+ were grown using the Bridgman technique. From highly resolved polarized absorption and luminescence measurements at 15 and 4.2 K, respectively, 101 crystal‐field levels from 27 different 2S+1LJ(4f11) multiplets of Er3+ in C3v symmetry were assigned. A Hamiltonian including 16 atomic and 6 crystal‐field parameters was fitted to a set of 87 crystal‐field levels and gave a rms standard deviation of 23.84 cm−1. Inclusion of one freely varying correlation crystal‐field (CCF) parameter lowered the overall rms standard deviation to 19.25 cm−1 and provided a dramatic improvement of the calculated crystal‐field splittings of specific CCF‐sensitive J multiplets.

Addition of a second lanthanide ion to increase the luminescence of europium(III) macrocyclic complexes

At present, the microscopic visualization of luminescent labels containing lanthanide(III) ions, primarily europium(III), as light-emitting centers is best performed with time-gated instrumentation, which by virtually eliminating the background fluorescence results in an improved signal to noise ratio. However, the use of the europium(III) macrocycle, Quantum DyeTM, in conjunction with the strong luminescence enhancing effect (cofluorescence) of yttrium(III) or gadolinium(III), can eliminate the need for such specialized instrumentation. In the presence of Gd(III), the luminescence of the Eu-macrocycles can be conveniently observed with conventional fluorescence instrumentation at previously unattainable low levels. The Eu(III) 5DO yields 7F2 emission of the Eu-macrocycles was observed as an extremely sharp band with a maximum at 619 nm and a clearly resolved characteristic pattern. At very low Eu- macrocycle concentrations, another sharp emission was detected at 614 nm, arising from traces of Eu(III) present in even the purest commercially available gadolinium products. Discrimination of the resolved emissions of the Eu-macrocycle and Eu(III) contaminant should provide a means to further lower the limit of detection of the Eu-macrocycle.

Methods to increase the luminescence of lanthanide (III) macrocyclic complexes

Simultaneous detection of both a Eu(III) and a Sm(III) Quantum Dye is now possible because the enhanced luminescence of the Eu(III) and Sm(III) macrocycles occurs in the same solution and with excitation at the same wavelengths between 350 to 370 nm. Since DAPI is also excited between 350 to 370 nm, it is possible to use common excitation optics and a single dichroic mirror for measuring two molecular species and DNA. The narrow emissions of these macrocycles can be detected with negligible overlap between themselves or with DAPI-stained DNA. This will permit precise pixel by pixel ratio measurements of the Eu(III) macrocycle to Sm(III) macrocycle, and of each macrocycle to DNA> This technology should be applicable to antibodies, FISH, comparative genomic hybridization, and chromosome painting. Cofluorescence of the Tb(III)-macrocycle has also been obtained under different conditions. The luminescence of these lanthanide macrocycles can be observed with conventional fluorescence instrumentation previously unattainable low levels. Thus, it will be possible to employ narrow bandwidth lanthanide luminescent tags to identify three molecular species with a conventional microscope.

Materials characterization, optical spectroscopy, and laser damage studies of electrochromically and photochromically damaged KTiOPO4 (KTP)

The techniques utilized to study the surface and bulk properties of KTiOPO4 (KTP) were Rutherford backscattering (RBS), particle induced x-ray emission (PIXE), secondary ion mass spectrometry (SIMS), optical absorption and emission spectroscopy, and controlled laser damage. RBS and SIMS results provide strong evidence for potassium ion and titanium ion migration from the bulk to the electrode surface under an applied DC voltage. Optical measurements suggest the presence of Ti3+ ions in pristine, EC and PC damages KTP. Catastrophic damage was induced models will be presented to rationalize the RBS, PIXE and SIMS data for the impurities, and a damage mechanism consistent with the findings of the laser damage and optical absorption and emission experiments will be discussed.

Spectroscopic analysis of infrared DIAL measurements

A combined experimental and computational approach utilizing CO2 infrared gas lasers and chemometric multivariate analysis was employed to detect chemicals and their concentrations in the open atmosphere under controlled release conditions. Absorption spectra of four organic gases were collected in the laboratory by lasing 40 lines of a Synrad 15 W CO2 laser in the 9.3 to 10.8 micron range. Several chemometric calibration models were constructed based on this IR data using the Partial Least Squares computational technique. The chemometric models were used to analyze in near real time the field DIAL data acquired over this exact wavelength range at round trip distances of 7 and 13 km. It will be shown that the ability to predict the chemicals and their respective concentrations depends on a variety of factors. In 39 of the 45 experiments, the identities of the released chemicals were correctly identified without predictions of false positives or false negatives. Under the best field conditions, we achieved predictions of absolute concentrations within 30% of the actual values.

Atmospheric effects on CO/sub 2/ differential absorption lidar performance

CO/sub 2/ differential absorption lidar (DIAL) performance can be adversely affected by the ambient atmosphere between the laser transmitter and the target through a number of different processes. This work addresses two sources of atmospheric interference with multi-spectral CO/sub 2/ DIAL measurements: effects due to beam propagation through atmospheric turbulence and extinction due to absorption by atmospheric gases. The authors compare the effective beam size after propagation to predictions from a beam propagation model that includes turbulence effects such as beam steering and beam spreading. They also compare the experimental measurements of atmospheric extinction to those predicted by both a standard atmospheric transmission model (FASCODE) and a chemometric analysis.

Development of frequency-agile high-repetition-rate CO{sub 2} DIAL systems for long range chemical remote sensing

Issues related to the development of direct detection, long- range CO2 DIAL systems for chemical detection and identification are presented and discussed including: data handling and display techniques for large, multi-(lambda) data sets, turbulence effects, slant path propagation, and speckle averaging. Data examples from various field campaigns and CO2 lidar platforms are used to illustrate the issues.