On-the-Fly Simulation of Two-Dimensional Fluorescence–Excitation Spectra
The Journal of Physical Chemistry Letters,
Journal Year:
2024,
Volume and Issue:
15(34), P. 8728 - 8735
Published: Aug. 20, 2024
Two-dimensional
(2D)
fluorescence-excitation
(2D-FLEX)
spectroscopy
is
a
recently
proposed
nonlinear
femtosecond
technique
for
the
detection
of
photoinduced
dynamics.
The
method
records
time-resolved
fluorescence
signal
in
its
excitation-
and
detection-frequency
dependence
hence
combines
exclusive
excited
state
dynamics
(fluorescence)
with
signals
resolved
both
excitation
emission
frequencies
(2D
electronic
spectroscopy).
In
this
work,
we
develop
an
on-the-fly
protocol
simulation
2D-FLEX
spectra
molecular
systems,
which
based
on
interfacing
classical
doorway-window
representation
spectroscopic
responses
trajectory
surface
hopping
simulations.
Applying
methodology
to
gas-phase
pyrazine,
show
that
can
deliver
detailed
information
otherwise
obtainable
via
attosecond
spectroscopy.
Language: Английский
Transient-Absorption Pump-Probe Spectra as Information-Rich Observables: Case Study of Fulvene
Molecules,
Journal Year:
2025,
Volume and Issue:
30(7), P. 1439 - 1439
Published: March 24, 2025
Conical
intersections
(CIs)
are
the
most
efficient
channels
of
photodeactivation
and
energy
transfer,
while
femtosecond
spectroscopy
is
main
experimental
tool
delivering
information
on
molecular
CI-driven
photoinduced
processes.
In
this
work,
we
undertake
a
comprehensive
ab
initio
investigation
CI-mediated
internal
conversion
in
fulvene
by
simulating
evolutions
electronic
populations,
bond
lengths
angles,
time-resolved
transient
absorption
(TA)
pump-probe
(PP)
spectra.
TA
PP
spectra
evaluated
fly
combining
symmetrical
quasiclassical/Meyer–Miller–Stock–Thoss
(SQC/MMST)
dynamics
doorway-window
representation
spectroscopic
signals.
We
show
that
simulated
reveal
not
only
population
but
also
key
nuclear
motions
as
well
mode–mode
couplings.
demonstrate
signals
observables:
They
can
be
considered
information-rich
purely
theoretical
observables,
which
deliver
more
than
conventional
populations.
This
extracted
appropriate
analyses
Language: Английский
Broadband Interferenceless Perfect Absorption in Hexagonal Boron Nitride and Lithium Fluoride Hyperbolic Metamaterial
Advanced Photonics Research,
Journal Year:
2025,
Volume and Issue:
unknown
Published: May 15, 2025
Interferenceless
perfect
absorption
holds
significant
promise
for
applications
in
photodetection,
photovoltaics,
and
medical
diagnostics.
In
this
study,
an
effective
composite
metamaterial
with
nanoscale
thickness,
composed
of
hexagonal
Boron
nitride
(
h
BN)
lithium
fluoride
(LiF)
layers
is
presented.
Using
medium
approximation
theory,
the
proposed
design
achieves
broadband
interferenceless
absorption,
independent
polarization,
either
transverse
magnetic
or
electric.
The
structure
employs
a
noninterferometric
approach,
enabling
near‐zero
reflectance
over
wide
incident
angle
().
Notably,
by
adjusting
relative
layer
thicknesses,
BN–LiF
offers
substantial
control
its
characteristics.
frequency
can
be
blue‐shifted
increasing
BN
thickness
red‐shifted
LiF
thickness.
This
flexible
tunability
makes
ideal
candidate
infrared
sensing,
other
light‐manipulation
technologies.
Language: Английский
Interconnection between Polarization-Detected and Population-Detected Signals: Theoretical Results and Ab Initio Simulations
Journal of Chemical Theory and Computation,
Journal Year:
2024,
Volume and Issue:
20(17), P. 7560 - 7573
Published: Aug. 26, 2024
Most
of
spectroscopic
signals
are
specified
by
the
nonlinear
laser-induced
polarization.
In
recent
years,
population-detection
becomes
a
trend
in
femtosecond
spectroscopy.
Polarization-detected
(PD)
and
population-detected
fundamentally
different,
because
they
determined
photoinduced
processes
acting
on
disparate
time
scales.
this
work,
we
consider
fluorescence-detected
(FD)
N-wave-mixing
(NWM)
signal
as
representative
example
signals,
derive
rigorous
expression
for
signal,
discuss
its
approximate
variants
suitable
numerical
simulations.
This
leads
us
to
definition
phenomenological
FD
(PFD)
which
contains
special
case
all
definitions
available
literature.
Then
formulate
prove
population-polarization
equivalence
(PPE)
theorem,
states
that
PFD
NWM
produced
(possibly
strong)
laser
pulses
can
be
evaluated
conventional
PD
effective
polarization
is
transition
dipole
moment
operator.
We
use
PPE
theorem
construction
ab
initio
protocol
simulation
4WM
signals.
As
an
example,
calculate
electronic
two-dimensional
(2D)
spectra
gas-phase
pyrazine
compare
them
with
corresponding
2D
spectra.
Language: Английский
Ultrafast charge carrier dynamics of methylammonium lead iodide from first principles
Electronic Structure,
Journal Year:
2024,
Volume and Issue:
6(3), P. 037001 - 037001
Published: June 24, 2024
Abstract
Methylammonium
lead
iodide
(MAPbI
3
)
has
been
a
major
focus
of
photovoltaic
research
for
the
last
decade.
The
unique
interplay
between
structural
and
electronic
properties
this
material
contributes
to
its
exciting
optical
especially
under
action
an
ultrafast
laser
pulse.
First-principles
methods
like
real-time
time-dependent
density
functional
theory
(RT-TDDFT)
enable
performing
corresponding
simulations
without
aid
empirical
parameters:
gained
knowledge
can
be
applied
future
studies
other
complex
materials.
In
work,
we
investigate
charge-carrier
dynamics
nonlinear
response
MAPbI
excited
by
resonant
pulse
above
gap.
First,
examine
in
static
regime.
Next,
impinge
system
with
femtosecond
field
varying
intensity
follow
evolution
photoexcited
carrier
density.
A
pronounced
intensity-dependent
is
observed,
manifested
high-harmonic
generation
trends
number
electrons
excitation
energy.
Our
results
provide
relevant
indications
about
behavior
strong
coherent
radiation
confirm
that
RT-TDDFT
viable
tool
simulate
photo-induced
materials
from
first
principles.
Language: Английский