Latest Publication

Anderson, J., R. Massaro, Glaspell, G., Bernard, W. and O. Weatherbee.
2008. Hyperspectral Fluorescence Remote Sensing of Landscape Molecular
Probes. Accepted American Society of Photogrammetry and Remote Sensing
(ASPRS) National Meeting, April 28- May 1, 2008. Portland, Orgeon.

Vapor Phase Synthesis of Upconverting Y2O3 Nanocrystals Doped with Yb3+, Er3+, Ho3+, and Tm3+ to Generate Red, Green, Blue, and White Light.

Glaspell, Garry; Anderson, John; Wilkins, James R.; El-Shall, M.
Samy. Department of Chemistry, Virginia Commonwealth University,
Richmond, VA, USA. Journal of Physical Chemistry C (2008),
112(30), 11527-11531. Publisher: American Chemical Society, CODEN:
JPCCCK ISSN: 1932-7447. Journal written in English. AN
2008:804676 CAPLUS

Abstract

We report the vapor phase synthesis of upconverting Y2O3 nanocrystals
doped with Yb3+, Er3+, Ho3+, and Tm3+ to generate red, green, blue, and
white light. Incorporating Er3+ within the Yb3+ doped Y2O3 nanocrystals
under 980 nm laser excitation produced orange and yellow upconversion
luminescence tunable by varying the Yb3+ concn. The Yb3+, Er3+, and
Tm3+ codoped Y2O3 nanocrystals exhibited nearly equal intensities of the
red, green, and blue emissions upon 980 nm laser excitation. White
light can be produced by adjusting the concns. of the Ln3+ ions within
the Y2O3 nanocrystals.

Formation of rare-earth upconverting nanoparticles using laser vaporization controlled condensation.

Glaspell, Garry; Wilkins, James R.; Anderson, John; El-Shall, M.
Samy. Virginia Commonwealth Univ. (USA) and U.S. Army Research and
Development Ctr., USA. Proceedings of SPIE (2008), 6940(Pt. 1,
Infrared Technology and Applications XXXIV), 69403B-69403B-7.
Publisher: Society of Photo-Optical Instrumentation Engineers, CODEN:
PSISDG ISSN: 0277-786X. Journal written in English. AN
2008:697307 CAPLUS

Abstract

Rare earth doped upconverting nanoparticles have been synthesized via
laser vaporization controlled condensation (LVCC) and their
photoluminescence properties were characterized using 980 nm laser diode
excitation. This procedure is highly tunable, specifically by
increasing the Yb3+ to Er3+ concn. the obsd. green emission decreases
and the obsd. red emission increases. We have also shown that nearly
equal peaks of blue, green and red emissions producing a virtually white
upconverter could be synthesized by appropriately mixing Tm3+, Ho3+, and
Er3+. We have also investigated the upconversion efficiency in a
variety of lattices including Y2O3, Gd2O3 and La2O3. TEM confirmed that
the as-formed particles were 10 nm in size and XRD indicated that the
overall crystal structure was predominately cubic.

Synthesis of Nanocrystalline TiO2 Particles and Their Structural Characteristics.

Manivannan, A.; Glaspell, G.; Dutta, P. Department of Physics,
West Virginia University, Morgantown, WV, USA. Journal of Cluster
Science (2008), 19(2), 391-399. Publisher: Springer, CODEN: JCSCEB
ISSN: 1040-7278. Journal written in English. AN 2008:557637 CAPLUS

Abstract

Controlled nanosized TiO2 particles of 4-10 nm were synthesized by a
simple hydrolysis method followed by calcination at different temps.
These particles were investigated using X-ray diffraction (XRD),
Photoacoustic/Fourier transform IR (PA/FTIR) spectroscopy, Raman
spectroscopy and ESR (ESR) spectroscopy to understand their structural
properties. X-ray diffraction studies confirmed the anatase phase of
the particles where as the PA/FTIR revealed the bands around 1,500 and
3,300 cm-1 due to -OH bands. ESR spectroscopic investigations carried
out from 5 to 300 K indicated the presence of an ESR line at g = 2.00
emerging from radical species. It is significant to note that the
intensity of the ESR line decreased as the particle size increased.

Growth and Characterization of ZnO, SnO2 and ZnO/SnO2 Nanostructures from the Vapor Phase.

Fouad, O. A.; Glaspell, G.; El-Shall, M. S. Central
Metallurgical Research and Development Institute (CMRDI), Cairo,
Egypt. Topics in Catalysis (2008), 47(1-2), 84-96. Publisher:
Springer, CODEN: TOCAFI ISSN: 1022-5528. Journal written in
English. AN 2008:340240 CAPLUS
Abstract
Zinc oxide (ZnO), tin dioxide (SnO2) and compds. ZnO/SnO2 (ZTO)
nanostructures have been synthesized successfully from the vapor phase
without a catalyst using three different approaches. XRD analyses
showed that ZnO with a wurtzite crystal structure, SnO2 with a rutile
crystal structure and zinc stannate (ZnSnO3) and/or dizinc stannate
(Zn2SnO4) were condensed from the vapor phase when Zn and/or Sn metal
powders or their oxides individually or mixed were used as the starting
materials. The formation of either zinc or dizinc stannate was
controlled by the Zn/Sn ratio and growth technique. SEM and TEM
investigations showed that ZnO grew mainly in the form of wires, rods
and belts. These are believed to be originated from the common tetrapod
structure of ZnO. While SnO2 grew in the form of tetragonal rods with
rectangle-like cross section and nanoparticles, ZTO grew in the form of
nanobelts. The final length, width and thickness were as low as 40, 10
and 5 nm, resp. The driving forces for growth of nanowires, nanorods,
nanobelts, and nanoparticles were found to be vapor d. or supersatn.,
temp., pressure and location of deposition from the source materials.
The optical absorbance and photoluminescence spectra of all samples
showed excitonic character at room temp. implying good crystal quality,
and high photocurrent properties suggesting possible applications in
nanoscaled functional devices such as optoelectronics and gas sensors.

Nanocatalysis on Supported Oxides for CO Oxidation.

Glaspell, Garry; Hassan, Hassan M. A.; Elzatahry, Ahmed; Abdalsayed,
Victor; El-Shall, M. Samy. Department of Chemistry, Virginia
Commonwealth University, Richmond, VA, USA. Topics in Catalysis
(2008), 47(1-2), 22-31. Publisher: Springer, CODEN: TOCAFI ISSN:
1022-5528. Journal written in English. AN 2008:340239 CAPLUS

Abstract

Active gold and palladium nanoparticles supported on a variety of oxides
(CeO2, ZrO2, Al2O3, SiO2, MgO and ZnO) were synthesized using laser
vaporization and microwave irradn. methods. The catalytic activities
for CO oxidn. on the nanoparticle catalysts were evaluated and compared
among different oxide supports. The effect of shape on the catalytic
activity is demonstrated by comparing the activities of the Au and Pd
catalysts deposited on MgO nanocubes and ZnO nanobelts. The Au/CeO2
nanoparticles deposited on MgO nanocubes exhibit high catalytic activity
and stability. The enhanced catalytic activity is attributed to the
presence of a significant concn. of the corner and edge sites in MgO
nanocubes. The Au- and Pd-doped Mn2O3 nanoparticles show promising
results for the low temp. CO oxidn. Several approaches for
incorporating the Au and Pd nanocatalysts within mesoporous oxide
supports are presented and discussed.

Laser synthesis of bimetallic nanoalloys in the vapor and liquid phases and the magnetic properties of PdM and PtM nanoparticles (M = Fe, Co and Ni).

Abdelsayed, Victor; Glaspell, Garry; Nguyen, Minh; Howe, James M.; Samy
El-Shall, M. Department of Chemistry, Virginia Commonwealth
University, Richmond, VA, USA. Faraday Discussions (2008),
138(Nanoalloys), 163-180.

In this work, we present several examples of the synthesis and
characterization of bimetallic nanoparticle alloys using the Laser
Vaporization Controlled Condensation (LVCC) method. In the first
example, the vapor phase synthesis of Au-Ag, Au-Pd, and Au-Pt
nanoparticle alloys are presented. The formation of nanoalloys is
concluded from the observation of one plasmon absorption band at a
wavelength that varies linearly with the gold mole fraction in the
nanoalloy. Both XRD data and HRTEM-EDX data confirm the formation of
nanoparticle alloys and not simply mixts. of the two metal
nanoparticles. Irradn. of a mixt. of Au/Ag nanoparticles dispersed in
water with the 532 nm unfocused laser results in efficient alloying
while the 1064 nm laser radiation results only in evapn. and size redn.
of the unalloyed nanoparticles. Selective absorption of the femtosecond
780 nm radiation by large Au aggregates results in the formation of
smaller aggregates with fractal structures, and no evidence for the
Au-Ag alloy formation. The synthesis of palladium and platinum
nanoparticles alloyed with transition metals such as iron and nickel
using the LVCC method is also presented. The alloyed nanoparticles
(FePd, FePt, NiPd, NiPt, and FeNi) are found to be superparamagnetic.