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B. Zachhuber, C. Gasser, G. Ramer, Engelene Chrysostom, B. Lendl:
"Depth profiling for the identification of unknown substances and concealed content at remote distances using time-resolved stand-off Raman spectroscopy";
Applied Spectroscopy, 66 (2012), 8; S. 875 - 881.

Time-resolved stand-off Raman spectroscopy was used to determine both
the position and identity of substances relative to each other at remote
distances (up to tens of meters). Spectral information of three xylene
isomers, toluene, and sodium chlorate was obtained at a distance of 12 m
from the setup. Pairs and triplets of these samples were placed at varying
distances (10-60 cm) relative to each other. Via the photon time of flight
the distance between the individual samples was determined to an
accuracy of 7% (corresponding to a few cm) of the physically measured
distance. Furthermore, at a distance of 40 m, time-resolved Raman depth
profiling was used to detect sodium chlorate in a white plastic container
that was non-transparent to the human eye. The combination of the
ranging capabilities of Raman LIDAR (sample location usually determined
using prior knowledge of the analyte of interest) with stand-off
Raman spectroscopy (analyte detection at remote distances) provides the
capability for depth profile identification of unknown substances and
analysis of concealed content in distant objects. To achieve these results, a
532 nm laser with a pulse length of 4.4 ns was synchronized to an
intensified charge-coupled device camera with a minimum gate width of
500 ps. For automated data analysis a multivariate curve resolution
algorithm was employed.

http://dx.doi.org/10.1366/12-06602