Ultraviolet Resonant Raman Enhancements in the Detection of ...

Currently,
there
are
a
variety
of
techniques
used
to
detect
explosives:
sniffing
explosive
 vapors
 (e.g.,
 fluorescence
 quenching
 and
 ion
 mobility
 spectroscopy),
imaging
 bulk
 explosives
 (e.g.,
 x‐ray
 backscattering
 and
 millimeter
 wave
 imaging),
and
spectroscopic
detection
of
explosives
(e.g.,
infrared,
Raman,
and
laser‐induced
breakdown
 spectroscopy
 techniques,
 and
 nuclear
 techniques).
 
 Due
 to
 the
drawbacks
experienced
by
all
explosive
detection
systems,
it
is
highly
desirable
to
combine
 detection
 systems
 in
 orthogonal
 approaches [1],
 meaning
 detection
methods
 should
 significantly
 differ
 in
 detection
 modality
 to
 capitalize
 upon
 the
strengths
 of
 individual
 techniques
 while
 minimizing
 overall
 system
 weaknesses.
When
orthogonal
systems
are
used
optimally
it
is
possible
to
obtain
a
probability
of
detection
and
false
alarm
rate
that
is
more
favorable
than
any
individual
detection
modality.
This
 research
 focuses
 on
 fundamental
 aspects
 of
 resonance
 Raman
spectroscopy
 as
 applied
 to
 select
 HE
 materials
 to
 advance
 our
 current
understanding
and
potentially
improve
HE
detection
at
standoff
distances.
B. BACKGROUND OF PREVIOUS WORK
Previous research into standoff detection of explosives using Raman spectroscopy
conducted by J. C. Carter’s research group at Lawrence Livermore National Laboratory
and S. K. Sharma’s research group at the University of Hawaii provide the foundation of
this investigation. Each of the aforementioned research groups has completed
experiments that demonstrate the initial feasibility of using normal Raman spectroscopy
to detect explosives at standoff distances; however, it is a much greater challenge to
demonstrate a technology’s military utility since this involves proposed concepts of
operations, theorizing system required performance parameters, and utilizing more
representative target sets.
The work completed in this thesis exploits the previous results derived from work
from several research groups investigating standoff Raman and resonance Raman to
further improve the ability to detect high explosives at standoff distances by assessing the
potential gains achievable using resonance Raman to detect explosives.
2