Raúl Baragiola, Engineering Physics
Research: Laboratory Astrophysics – optical characterization and
simulation of micrometeorite impact via pulsed laser energy deposition.
Fellows:
Mark Loeffler - Simulation of micrometeorite impact on asteroids with
pulsed laser beams. Characterization by FTIR and
electron spectroscopy
Devin Pugh -
Characterization of thin film growth by diffuse laser
scattering, interferometry, and microbalance techniques.
Application to microporous amorphous ice.
Ben Teolis -
Ultraviolet spectroscopy of ozone production in
condensed gases by ion and photon irradiation.
Application to icy satellites of Jupiter and Saturn.
Associates:
Catherine Dukes, Jan Lorincik
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Mark Loeffler research on space weathering
of asteroids
Transient heating of olivine by laser pulse
produces changes in near IR absorption
bands similar to what is observed on
asteroids, and attributed to the impact of
micrometeorites and solar wind ions. XPS
results show that irradiation forms iron
precipitates. Unlike previous research, Mark
will do reflectance measurements in situ, to
prevent oxidation by air.
Electron microscopy will be used to
understand the relationship between Fe
nanoparticle size and distribution and the
reddening of the mineral due to irradiation.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Lou Bloomfield, Dept. of Physics
Research: Dynamics of Cluster Structure, Isomerization, and
Photodissociation.
Associates: Andy Dally & Songbai Ye
Photodesorption of Alkali Negative Ions
from Alkali-Halide Cluster Anions
Using picosecond laser pulses, we have
examined the photodesorption of negatively
charged alkali ions from alkali-halide clusters.
These fragile atomic ions, with extra electrons
that are only barely held in place, have not
been observed previously among the fragments
leaving alkali-halide (salt) surfaces following
exposure to light.
We find this unusual desorption in a broad class
of negatively charge alkali-halide clusters—
those containing two or more electrons that are
not involved in the salt’s ionic bonding. The
desorption starts via electronic excitation, with
the excitation decaying quickly to eject the
outgoing negative ion.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Thermal Isomerization Dynamics and
Melting in Alkali-Halide Clusters
We have produced (a) ensembles of cluster
ions with enough thermal energy to undergo
rapid changes in geometric structure, a process
known as thermal isomerization. Because they
switch quickly from one isomeric form to
another, these clusters are effectively molten.
To study the dynamics of these clusters, we use
an ultrashort laser pulse (b) to selectively
destroy most of the clusters in one isomeric
form. Thermal isomerization immediately
begins to repopulate the missing form. We use
a second laser pulse to measure the isomer
populations at later times (c), and thus learn
about the structure, energetics, and thermal
properties of these tiny systems.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
James Fitz-Gerald,
Dept. of Materials Science and Engineering
Research: Laser based processing of organic and inorganic materials.
In-situ plasma characterization, Materials characterization
Associate:
Andrew Mercado - Matrix Assisted Pulsed Laser Evaporation
(MAPLE) of Biodegradable Polymers: Excimer (ns) laser processing
laser pulse
substrate
• The volatile solvent
absorbs a large % of the
frozen target
laser pulse. Upon
heating, the solvent
gently desorbs the
organic molecule.
volatile solvent is pumped away
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
GA
O
CH3
[ ][ ]
3
4
O
O
Andrew Mercado’s Research on
MAPLE of a Biodegradable
Polymer - PLGA
1
LA
O
OH
O
CH3
2
(PLGA)
1H-Nuclear
Magnetic Resonance (NMR)
(b)
deuterated chloroform
CDCl3
Fluence: 0.18 J/cm2
Laser frequency: 20 Hz
21,000 pulses
100 mTorr Ar
(c)
Fluence: 0.18 J/cm2
Laser frequency: 10 Hz
10,000 pulses
100 mTorr Ar
1 µm
1 µm
Fluence: 0.43 J/cm2
Laser frequency: 20 Hz
4,000 pulses
100 mTorr Ar
(e)
Fluence: 0.30 J/cm2
Laser frequency: 20 Hz
30,000 pulses
100 mTorr Ar, 60° tilt
(a)
Native
0.26 J/cm2
20 Hz
30,000 pulses
100 mTorr Ar
PLGA2
4
3
1
A r b itr a r y
2
0.34 J/cm2
20 Hz
30,000 pulses
100 mTorr Ar
PLGA5
0.43 J/cm2
20 Hz
4,000 pulses
100 mTorr Ar
PLGA11
0.56 J/cm2
20 Hz
32,000 pulses
100 mTorr Ar
PLGA8
(d)
1 µm
8
7
6
5
4
3
2
1
PLGA thin film
Si wafer
100 nm
0
p p m
NMR spectra (a) comparing the native and deposited thin films and scanning electron microscopy
(SEM) images of the deposited thin films (b-e). NMR spectra of the deposited films are in good
agreement with the native material, with the exceptions as noted. SEM micrographs show trends in
energy and deposition rate, both of which have a direct relationship to the entrainment process.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Thomas Gallagher, Dept. of Physics
Research: Interactions of Rydberg atoms with radiation fields and
with each other.
Fellows:
Edward Shuman – Dielectronic Recombination in crossed static and
microwave fields.
Ken Baranowski - Microwave ionization of alkali atoms.
Associate:
Michael Bajema – Control of the branching ratio for autoionization with
the time delay between femtosecond laser pulses.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Dielectronic Recombination signals with an
11 GHz field polarized perpendicular to a
static field. The classical limit is the solid
bold line. The signals above the classical
limit are not present without the microwave
field.
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
9.9
19.7
29.7
38.5
48.8
58.4
67.0
78.5
88.3
97.6
107.4
118.7
127.2
137.8
Static electric field (V/cm)
Dielectronic Recombination is the
recombination of an ion and an electron via
an autoionizing Rydberg state. It is
enhanced by a static field below the
classical limit, but does not occur above the
classical limit. Adding a microwave field
polarized perpendicular to the static field
enables recombination above the classical
limit. The mechanism is m transitions to
more stable high m states.
DR signal (arb. units)
Edward Shuman’s Research on Dielectronic
Recombination
-120-100 -80 -60 -40 -20 0
-1
Relative binding energy (cm )
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Tatiana Globus, Boris Gelmont, Dept. of
Electrical and Computer Engineering
Research:Terahertz Wave Interaction with Biological
Macromolecules (Experiment + Modeling)
Fellow:
Tiffany Mapp - Computer modeling of submillimeter wave
absorption of short biological molecules.
Associate:
Maria Bykhovskaia- Theoretical Prediction of Absorption
Spectra.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Tiffany Mapp’s Research on Computer
Modeling of Submillimeter Wave Absorption
of Short Biological Molecules
Absorption Spectrum PolyAPolyU (z)
g= 1
THEORETICAL PREDICTION OF ABSORPTION
SPECTRA
Absorption of PolyAPolyU
g= 0.5
0.025
0.016
0.014
0.020
0.012
0.015
Absorption
Frequencies
<300 cm -1
Torsion angles
Absorption
0.010
0.008
0.006
0.004
0.010
0.005
0.002
0.000
0.000
Energy minimum
Normal modes
Spectra
Absorption spectra are calculated using the normalized
dipole moment p
 ()  g2  (pk)2 / ( (k2 - 2 )2 + g2 2 )
0
10
20
30
Frequency (cm-1)
40
50
60
0
10
20
30
40
50
Frequency (cm-1)
Absorption spectra of double stranded RNA fragments
Poly A-Poly U calculated for oscillator decay values
g=1 cm-1 and g =0.5 cm -1 and for two different
orientation of electric field of radiation relative to the
long axes of a molecule.
RNA Infra-red active modes have been calculated directly from the base pair sequence and topology of a molecule
Spectra are sensitive to a molecule’s composition
Intense peak is predicted at the lowest frequency ~ 2 cm-1.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
60
Ian Harrison, Dept. of Chemistry
Research: Laser induced photochemistry and spectroscopy at surfaces,
reaction dynamics of catalysis.
Fellows:
Alex Bukoski - Microcanonical rate theory at surfaces: Application to
non-equilibrium laser, electron, and collisionally induced
processes at surfaces.
Kristin Buck - Surface photochemistry and spectroscopy: Broadband
ir/visible sum frequency generation,ultrafast
photochemistry of adsorbates
Associates:
Rob Zehr, Neel Samanta - Adsorbate photochemical dynamics: ns lasers.
Todd Schwendemann Electron transfer chemistry of single adsorbates
studied by scanning tunneling microscopy.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Alex Bukoski’s Research on Microcanonical
Unimolecular Rate Theory at Surfaces
10-1
CH4 : J = 2 , v3 = 1 Eigenstate
Tn = 400 K
Initial Sticking Coefficient
10-2
10-3
10-4
10-5
10-6

E0 = 67 kJ/mol

E0 = 53 kJ/mol
PC - MURT 
10-7
20
30
40
50
60
70
Normal Translational Energy [kJ/mol]
Schematic depiction of the kinetics and
energetics of activated dissociative
chemisorption. Zero-point energies are
implicitly included within the potential
energy curve along the reaction coordinate.
Dissociative chemisorption of a methane
molecular beam incident on a Ni(100)
surface with and without infrared laser
excitation of the n3 antisymmetric C-H
stretching vibration of the gas-phase CH4.
Comparison of experiment to theory with
different reaction threshold energies, E0.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Bob Jones, Department of Physics
Research: Investigating the response of atoms and small molecules to intense
short laser pulses and the use of coherent light to view and control quantum
dynamics in atoms and molecules
Fellows:
Dan Pinkham - Characterization and control of ultra-fast laser pulse shapes
for manipulation of intense field fragmentation processes in small
molecules and clusters.
Brett Sickmiller - Creation of sub-20 femtosecond VUV light pulses from
intense near infrared light via high harmonic generation.
Associates:
Merrick DeWitt, Eric Wells - Investigation of intense laser ionization and
fragmentation in molecules and small clusters
Santosh Pisharody, Jason Zeibel, Jeremy Murray-Krezan- Manipulation of
electronic wavepackets for probing coherent time-dependent processes
in atoms
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
+
S Yield
Pinkham/Well’s Research on Closed Loop Control
of Intense Laser Fragmentation of Clusters
S2 Yield
Laser
0.18
0.16
0.14
2.9x
+
0.12
0.10
Yield
1 kHz
800 nm
120 fsec
3.6x
0.08
0.06
0.04
0.02
0.00
-0.02
0.0
-5
1.0x10
-5
2.0x10
-5
3.0x10
Transform S + / S+
2
+
S / S2
+
TOF
Schematic of a closed loop laser control apparatus.
A genetic algorithm searches for the “best” laser
pulse to optimize a specified laser fragmentation
pattern. The algorithm controls a liquid crystal
based laser pulse shaper based on feedback from a
fragmentation experiment .
Typical results from a control experiment
using S8 as a target. The left most columns
show the S+ and S2+ product yields using an
unshaped 100 fsec laser pulse. The middle
and right hand columns show the same
product yields when the algorithm is told to
optimize the ratios S2+:S+ and S+:S2+,
respectively.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
James Landers, Dept. of Chemistry
Research: Analytical microchip technology for diagnostics and
biomedical research.
Fellows:
James Karlinsey
- Precision laser ablation of microstructures in glass chips
- Acousto-optic technology development for laser-induced
fluorescence detection on microchips
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
James Karlinsey’s Research on the
Development of Microchip Technology
5
488 nm
476 nm
4
RFU
3
514 nm
457 nm
2
1
Laser Machining with Femtosecond
Pulses: The SEM shows the exit plane of a
microscope slide, after exposure to 2 mJ pulses
fired at a 1 kHz repetition from a fs Regen laser
focused at 250 mm. The laser-drilled has small
dimensions (<100 µm) and will allow for
microfluidic connects between different layers in
a microdevice.
0
35
40
45
50
55
60
65
time/s
Multiline Ar+ Laser Scan: The RF applied to the
AOTF was scanned from 100-180 MHz (~450-700 nm)
at an interval of 0.5 MHz every 0.1 s. This offers new
approaches for controlling the addressing of lasers on
microchips.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Gabriel Laufer – Mechanical and Aerospace Engineering
Research: Remote sensing of the distribution of CH4 in the
stratosphere and of oceanic chlorophyll from sounding rockets
Fellows:
W. Clayton Nunnally- Wide Field of View Gas Filter
Correlation Radiometer for Sounding Rocket
Deployment
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Clayton Nunnaly’s research on measuring the
stratospheric distribution of CH4
Stratospheric Absorbance 3.2-3.4 microns
Temp:233K Pressure: 0.01atm Path 50km
1.00E+00
Absorbance(1-T)
7.50E-01
5.00E-01
2.50E-01
0.00E+00
3.46
3.38
WL (m)
Bandpass Filter
Schematic of the solar gas filter correlation
radiometer (GFCR). The system was
designed to detect CH4 at high specificity
using the absorption spectrum of solar
radiation. A wide field of view (FOV)
optical collection allows detection during
rocket ascent without the need for active
control.
3.31
CH4
3.24
HCL
Absorption spectra of atmospheric CH4 and HCl,
superimposed by the transmission curve of a
spectral-limiting bandpass filter. By correlating
this spectrum with the absorption by CH4 in a
sample cell within the system, optical densities
of 0.0001-0.001 atm-m can be measured at an
uncertainty of <0.3% and FOV >30 while
rejecting HCl interference.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Microscale Heat Transfer Lab
Professor Pamela Norris
Department of Mechanical and Aerospace Engineering
Research:
• Observe transient carrier phenomena on a subpicosecond timescale using
non-destructive optical techniques.
200 femtosecond laser in a pump-probe setup
• Contribute to the foundation for the continued development of nanoscale
technologies.
Measure critical properties of metals and semiconductors
Develop and verify models of transient carrier phenomena
• Fellow:
Rob Stevens -
Ultrafast carrier dynamics in a-Si:H and energy transport in
thin metallic films.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Rob Stevens’ Research on Ultrafast Carrier
Dynamics in a-Si:H Films
Chopper
500 Hz
Photodetector
Below is a series transmission
scans of intrinsic a-Si:H collected
using varying probe energies. The
decays indicated by scans are a
combination of thermalization of
hot electrons, recombination, and
trapping.
Pump:
1 kHz, ~100 fs,
625-1000nm,
20-120mJ
Sample
Probe:
Prism on
micropositioning
stage (0.1 mm res.)
1 kHz, ~100 fs,
white light
0.2
1.426
1.551
1.591
1.611
1.632
1.654
1.677
1.700
0
Lock-in Amp
- 0.2
T/T
Computer
Devising optical pump-probe techniques and models to
better understand the transient carrier phenomena of aSi:H films used by the photovoltaic industry. Primary
focus is on recombination mechanisms and the role of
band tail states.
eV
eV
eV
eV
eV
eV
eV
eV
- 0.4
- 0.6
- 0.8
-1
- 1.2
-1
0
1
2
3
4
5
Time (ps)
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
6
Brooks H. Pate, Dept. of Chemistry
Research: unimolecular isomerization kinetics, solvent effects on
intramolecular vibrational dynamics, dynamic rotational spectroscopy
Fellows:
Pam Crum (2nd Year) - Reaction dynamics in gas and solution by
selective-excitation, broadband probe ultrafast IR
spectroscopy (ps pump - fs probe)
Kevin Douglass (2nd Year) - Time-domain 2D-Microwave spectroscopy of
high-energy isomerization reactions (using
Fourier transform signal acquisition)
Associates:
John Keske (Ph.D. 2001) - Rotational spectroscopy of isomerizing
molecules
Hyun Yoo (Ph.D. 2002) - Vibrational dynamics in gas and solution
Yehudi Self-Medlin (Ph.D. 2003) - Vibrational dynamics and
isomerization in gas and solution
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Vibrational Dynamics by Ultrafast Infrared Spectroscopy and
Dynamic Rotational Spectroscopy
Competition Between
Intramolecular and Solution Dynamics
3
FTMW 111 - 202 Excited
State Transition
Level Diagram
for Fluoroproyne
OH Stretch
CD3OH
kTOT = kIVR + kVER
3.0
Rotational Spectroscopy of Excited States by
IR - FTMW - MW Triple Resonance Spectroscopy
Direct Comparison of
Gas- and Solution-Phase Dynamics
H
2.0
0
1.0
CCl4
0.5
kVER = (67 ps)-1
0.0
0.0
0.5
1.0
1.5
11
2.0
2.5
3.0
-1
kIVR (10 s )
Rate (1011 s-1)
3
kTOT
IVR
Threshold
kIVR
2
202
0
30
60
90
150
10
2
log(3330cm-1)
3
4
F
13647.10 13647.75 13648.40
Frequency (MHz)
MW Frequency Scan to Measure
303 - 202 Rotational Transition
0
0.14
0
10
20
30
40
50
Acetylenic CH Stretch
C6H5CCH
IR
(3332.26 cm-1)
0
1
C
H
5
212
0
H
0.0
2
0
C
0.2
0.1
FTMW Monitor
(13647.75)
OH Stretch
(CF3)3COH
4
1
120
C
0.3
111
0
5
10
15
20
(JKaKc)
Intensity at Peak (V)
1.5
MW Scan
Intensity (V)
303
Absorption Change (mOD)
kTOT (1011 s-1)
0.4
2
2.5
0.12
0.10
0.08
0.06
0.04
0.02
0.00
26358.5
26359.5
26360.5
Frequency (MHz)
Time (ps)
Using the SELIM Ultrafast Laser Facility we have performed the first direct
comparison of the isolated molecule and solution phase vibrational energy
relaxation rates of polyatomic molecules. We find that solvent effects are minor
and that the total relaxation rate in solution is dominated by the purely
intramolecular dynamics. (Second plot: Gas (black), 0.05 M CCl4 solution (red))
The first measurements of the rotational spectrum
of a laser-prepared vibrational excited state by
Fourier transform microwave (FTMW) spectroscopy
is shown. This technique has also been extended to
include IR-MW-MW triple-resonance measurements.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Olivier Pfister, Dept. of Physics
Research: Quantum Optics and Quantum Information; experimental and
theoretical studies of continuous-variable entanglement.
Fellows:
Raphael Pooser, 2nd year Engineering Physics student (Ph.D.)
- Theory of interferometry at the Heisenberg limit.
- Design of a three-photon optical parametric oscillator and experimental
investigation of its quantum and classical properties.
Gregory Jennings, 2nd year Material Science Engineering student (M.S.)
- Study and characterization of periodically poled nonlinear optical ferroelectrics.
Darrell Gullatt, 1st year Engineering Physics student (Ph.D.)
- Laser frequency stabilization and characterization.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
QUANTUM OPTICS/QUANTUM INFORMATION
Pfister Labs, UVa Physics
• Entanglement of two quantum optical fields:
 Quantum teleportation: “the disembodied transfer of an unknown
quantum state from one location to another”
 Ultra-precise interferometry at the Heisenberg limit: measure optical phase
(N=photon number)
1
1
  k  r  t
  
N
N
Time-domain: ultrasensitive detection of phase shifts (e.g. gravitational waves)
Space-domain: ultra-high-resolution quantum imaging / quantum lithography.
•

Entanglement of three quantum optical fields:
 Quantum error correction
(quantum telecloning).
and parallel quantum communication
Cass Sackett, Dept. of Physics
Research: Laser cooling, Bose-Einstein condensation, and atom
interferometry
Fellow:
Jessica Reeves -Bose-Einstein condensation: Development of BEC
machine, application to atom-interferometric
measurement of inertial and interaction effects.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Jessica Reeves’s Research on Bose-Einstein
Condensation and Atom Interferometry
1
2
Schematic depiction of atom interferometry
with a Bose-Einstein condensate. A
stationary cloud of atoms can be split into
two pieces using laser manipulation, and
later recombined. The atomic wave
function will exhibit interference fringes
that depend on the phase difference
experienced.
Vacuum chamber constructed for BEC
experiment. Currently trapping ~109
atoms at T ~ 50 mK, and transferring
atoms to UHV cell for further cooling.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
University of Virginia
Suely Black, Department of Chemistry and CMR
Research: Ab initio electronic structure modeling of infinite structures by van der
Waals and covalent clusters
Fellows:
Cheryl Blumenberg -Theoretical study of urea clusters structures and
vibrational spectra using Hartree-Fock, DFT, and MP2 methods.
Kendra Brown - Determination of the electrostatic potential of the hydrogenterminated Si(100) 2x1 surface by ab inito methods for adsorption
studies.
Charmagne Harris - Calculation of the static first hyperpolarizabilities of
methyl-nitroaniline (MNA)
clusters.
Associates:
Chalette Sapp-Mobley - Theoretical study of the adsorption of MNA on the
hydrogen-terminated Si(100) 2x1 surface.
Sheena Inge - Application of semi-empirical/ab initio hybrid methods to model
the Si(100) 2x1 surface.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
Norfolk State University
Blumenberg’s urea cluster structure determination
using HF, DFT and MP2 methods
Allowed
degrees of
freedom in
geometry
optimization
Internal Dihedral Angle (º) OCNH,
6-31G** HF Optimized Geometries
30
25
20
15
10
5
0
0
1
2
3
4
5
6
7
8
# molecules in cluster
Clusters of up to seven urea molecules optimized with selected degrees of freedom to
reproduce the crystal arrangement. Relative internal molecular coordinates are allowed to
change. The OCNH dihedral angle decreases with increasing cluster size, approaching zero,
which corresponds to the value found in the crystal.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
Norfolk State University
Carl Bonner, Department of Chemistry and CMR
Research: Investigating the 1st and 2nd order hyperpolarizability of molecular
chromophores and polymers and the response transformation from individual
molecules to clusters to films.
Fellows:
LaQuita Huey – Measurement of two photon absorptivities in a
range of thiacyanine analogues for optical limiting
applications at Ti-Sapphire wavelengths
Associates:
Olu Bolden - Characterization of 1st hyperpolarizbility of
chromophores chiral or other tertiary structures, such
as Ni-salophen (binapthol) compounds
NSF IGERT: Science and Engineering of Laser Interactions with Matter
Norfolk State University
HyperRayleigh Scattering Measuerments of
the 1st Hyperpolariability of Ni Salophen
200
I2/I (arb units) x 10
chopper
Signal of 21 mM (mV)
Signal of 12 mM (mV)
Signal of 7 mM (mV)
12
-23
Ar+ ion pumped Amplified
Ti-Sapphire Laser, 800 nm
150 fsec, 250kHz, 4 mJ
BPF
attenuator
IF
input ref
Lock-in amp
Computer
6
3
0
lens
beamdump
Schematic of HyperRayleigh Scattering (HRS) experiment.
The experiment measures the intensity of the second
harmonic of the Rayleigh scattered line. This intensity is
proportional to the square of the incident intensity. A
confocal cavity maximizes the collection efficiency.
The signal is
I(2) = G i Ni<HRS2>i I()2
which for a two component system of solute and solvent is
=G[ Ns<HRS2>s + Nc<HRS2>c ] I()2
Slope = 3.8443 x 10
esu
-38
150
pNA reference
DR-19
100
50
2
PMT
I(2) (mVolts)
9
0.0
0.5
1.0
1.5
I() (watt/cm ) x 10
2
2.0
11
2.5
0
Slope = 1.05443 x 10
0.0
2.0
4.0
6.0
8.0
10.0
12.0
3
14.0
Number Density (particle/cm ) x 10
The dependence of the signal on concentration
(expressed as number density) gives the
molecular hyperpolarizbility. Measurements are
made relative to a standard compound paranitrobenzene.
NSF IGERT: Science and Engineering of Laser Interactions with Matter
Norfolk State University
-41
18
Mikhail A. Noginov Department of Physics and CMR
Research: The effect of the diameter of the pumped spot on the threshold and the slope
efficiency of Nd0.5La0.5Al3(BO3)4 ceramic random powder lasers
Fellows:
Kaleem J. Morris, MS student (directly supported by IGERT)
Associates:
G. Zhu, MS student (not supported by IGERT directly)
M. Bahoura, research faculty (not supported by IGERT directly)
NSF IGERT: Science and Engineering of Laser Interactions with Matter
Norfolk State University
Study of random laser emission at different sizes of
the pumped spot
Input/Output curves
Threshold density vs. spot diameter
Experimental setup
NSF IGERT: Science and Engineering of Laser Interactions with Matter
Norfolk State University