The study of life in extreme environments is a critical component of Astrobiology. But many of the so-called
"extremophiles" are not readily cultivatable and therefore difficult to study under laboratory conditions. An example
of such an extremophile is the snow alga Chlamydomonas cd. nivalis which expresses still unstudied secondary
metabolites within its life cycle. In this paper, we present the first time the non-invasive single cell Raman
spectroscopy of the life cycle dependent metabolite composition of C. nivalis. These secondary metabolites are likely
related to the adaptation of C. nivalis to various stress factors. Normalized carotenoid Raman spectra intensities reveal
characteristic ratio differences that allow identification of life cycle stages and putative secondary metabolites.
Robust, tunable Surface enhanced Raman spectroscopy (SERS) substrates were created using the Langmuir-Blodgett
technique. Initial studies of Langmuir-Blodgettry were done with arachidic acid to optimize monolayer deposition
parameters. Hydrophilic and hydrophobic glass substrates were prepared and coated with arachidic acid. SERS
monolayer substrates were then made from Ag nanostructures. Deposition of Ag nanoparticles using the Langmuir
Blodgett technique resulted in clusters of Ag monolayers. The films were capable of SERS for Rhodamine 6G (R6G)
and a range of biomolecules. Raman imaging of these films revealed the overall distribution of the SERS effect. In
comparison of the enhancement performances, Ag nanowires were also deposited on glass substrates using Langmuir
Blodgettry. The resulting substrate consisted of oriented bundles of Ag nanowires. SERS of R6G was observed on
these bundles when the polarization of light was longitudinal to the wire axis. Raman imaging showed the distribution
of hotspots on the nanowire bundles.
Reversible, large-strain, bistable actuation has been a lasting puzzle in the pursuit of smart materials and
structures. Conducting polymers are bistable, but the achievable strain is small. Large deformations have been
achieved in dielectric elastomers at the expense of mechanical strength. The gel or gel-like soft polymers
generally have elastic moduli around or less than 10 MPa. The deformed polymer relaxes to its original shape
once the applied electric field is removed. We report new, bistable electroactive polymers (BSEP) that are
capable of electrically actuated strains as high as 335% area strain. The BSEP could be useful for constructing
rigid structures. The structures can support high mechanical loads, and be actuated to large-strain
deformations. We will present one unique application of the BSEP for Braille displays that can be quickly
refreshed and maintain the displayed contents without a bias voltage.
We explore the feasibility of using Raman imaging as a technique for identifying areas of high astrobiological interest
on Mars-like surfaces. This paper will discuss the technique, analysis, and possible deployment of rover mounted
instrumentation for identifying biogenic samples from Mars analog environments, such as the Mojave Desert and
Lassen Volcanic National Park. We also discuss using this technique for the non-destructive, in situ identification
snow algae found in harsh environments.
We present Raman spectroscopy analysis on laboratory and field sample analysis on several expeditions.
Our measurements in mineral and organic composition have demonstrated that both mineral and organic
species in low concentrations can be identified with Raman spectroscopy with no sample preparations
and without instrument probe contact to the samples. Our laboratory studies on cyanobacterial biomat,
and Mojave Desert rocks have demonstrated the promising potential for Raman spectroscopy as a nondestructive,
in situ, high throughput detection technique, as well as a desirable active remote sensing tool
for future planetary and space missions.
We report studies of the electropolymerized polypyrrole (PPy) films around vertically aligned bamboo-like multiwall carbon nanotube (MWNT) arrays. Raman spectroscopy has revealed large percentage dipolarons resulting from highly conjugated PPy. The expected high conductivity of PPy-MWNT composite has also demonstrated by electrochemical studies. The SEM and TEM microscopy observations of the high mechanical strength, dense packing and strong adhesion exhibited in this composite are results of the π-stacking between the PPy backbone and the aromatic MWNT sidewalls.
We present design, integration and test results for a field Raman spectrometer science payload, integrated into the Mars
Analog Research and Technology (MARTE) drilling platform. During the drilling operation, the subsurface Raman
spectroscopy inspection system has obtained signatures of organic and mineral compositions. We also performed ground
truth studies using both this field unit and a laboratory micro Raman spectrometer equipped with multiple laser
excitation wavelengths on series of field samples including Mojave rocks, Laguna Verde salty sediment and Rio Tinto
topsoil. We have evaluated laser excitation conditions and optical probe designs for further improvement. We have
demonstrated promising potential for Raman spectroscopy as a non-destructive in situ, high throughput, subsurface
detection technique, as well as a desirable active remote sensing tool for future planetary and space missions.
In recent years, there has been significant interest in using surface enhanced Raman scattering (SERS) and
optical fibers for chemical, biological, and environmental detections. The combination of SERS and optical fibers offers
the advantages of the molecular specificity of Raman scattering, huge enhancement factor of SERS, and flexibility of
optical fibers. In this paper, we report our work on the development of fiber biosensors based on SERS emphasizing on
recent progress in the fabrication of photonic crystal fiber (PCF) SERS sensors for highly sensitive molecular detection.
To increase the sensitivity, one needs to increase either the excitation laser power or the amount of analyte molecules in
the active region of the sensor. The high excitation intensity is not desirable for biosensors due to the low damage
threshold of live tissues or bio-molecules. In our investigation of various fiber configurations, hollow core (HC) PCFs
show the greatest advantages over all other types of fiber probes because of the large contact area. The hollow core
nature allows the analytes and SERS substrate to fill the inner surface of the air channels. In addition, by sealing the
cladding holes of the HCPCF, only the central hole will be open and filled with liquid samples. As both the light and the
sample are confined in the fiber core, the sensitivity is significantly improved. The newly developed liquid core PCF
sensor was tested in the detection of rhodamine 6G (R6G), human insulin, and tryptophan with good sensitivity due to
the enhanced interaction volume.
Semiconducting metal oxide nanowires represent a class of novel materials that are of superior
properties to naoparticles currently used in dye sensitized solar cell and polymer hybrid solar cells.
The quasi one-dimensional nanostructure and surface states of nanowires improve carrier mobility
and charge transfer through interface interactions of theses nanocomposite materials. Raman
spectroscopy, especially resonant Raman spectroscopy, is used to correlate nanomaterial synthesis
condition to the structural, optical and electric transport properties that are important to
photocatalysis, exciton transport and recombination and hydrogen storage mechanism. For example,
highly orientated ZnO nanowires studied with Raman and photoluminescence spectroscopy
demonstrated the high efficiency of the phonon and electron coupling. These results are compared
with that of other ZnO forms such as thin film, polycrystalline powder and solid. The Raman
bandwidths and shifts of nanowires revealed the phonon confinement in the quasi one-dimensional
nanostructures, which is further demonstrated with In2O3 nanowires at 5, 10, 20, 30 nm in diameters.
Room temperature photoluminescence results also show band gap shifts with nanowire dimensions.
Nanowire sizes, defects and strains, controlled by synthesis conditions, have shown to determine
band structure and optical phonon properties. We also discuss characterization and synthesis of
carbon nanotube based composite materials including polymer electropolymerization and
infiltration. Combining significantly enhanced mechanical compressive strength and excellent
electric conductivity, these composite materials offer potentials to fuel cell anode materials as
multifunctional hydrogen storage media.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.