Physical review. B./Physical review. B,
Год журнала:
2024,
Номер
110(7)
Опубликована: Авг. 2, 2024
By
frequency-time
spectroscopy,
microscopy,
and
electronic
structure
theory,
we
investigate
the
low
coverage
adsorption
of
Ca
on
an
Ag(111)
surface.
The
chemisorption
alkaline-earth
atoms
starting
from
their
closed
$4{s}^{2}$
shell
configuration
differs
that
open
$n{s}^{1}$
alkali-metal
because
they
retain
some
$4s$
electron
charge
can
involve
hybridization
with
low-lying
unoccupied
$3d$
orbitals.
Spectroscopic
investigation
by
three-photon
photoemission
(3PP)
reveals
states
dominant
3d-orbital
character,
as
confirmed
theory.
Coverage-specific
spectral
features
enable
attribution
to
two
distinct
phases
at
submonolayer
coverages,
which
are
atomic
scale
scanning
tunneling
microscopy
spectroscopy
measurements.
Furthermore,
time-resolved
3PP
a
resonant
two-photon
transition
between
occupied
$(\ensuremath{\sim}\ensuremath{-}0.3
\mathrm{eV})$
$(\ensuremath{\sim}2.7
s-
$d$-orbital
character.
Interferometric
measurements
probing
this
resonance
reveal
dephasing
time
$\ensuremath{\sim}21$
fs
population
lifetime
$\ensuremath{\sim}52$
for
transiently
populated
$d$-like
state
$\ensuremath{\sim}2.7$
eV
above
${E}_{F}$.
Contrary
atom
chemisorption,
characteristic
development
importance
adsorbate
Ag
substrate
interactions
cause
low-coverage
condensation
into
compact
islands.
Discovery
long-lived
$d$-character
informs
catalytic
optoelectronic
applications
element
Ca.
Progress in Surface Science,
Год журнала:
2024,
Номер
99(3), С. 100745 - 100745
Опубликована: Апрель 26, 2024
Semiconductor
interfaces
are
at
the
heart
of
functionality
many
devices
for
opto-electronic
applications.
At
these
interfaces,
importance
ultrafast
dynamics
–
processes
that
occur
on
sub-nanosecond
timescales
has
been
long
understood.
While
spectroscopic
studies
have
revealed
important
information,
there
remains
a
rich
array
physics
is
hidden
within
sub-micrometer
length
scales
when
using
spatially-averaged
techniques.
However,
powerful
tools
could
access
material
in
semiconductors
simultaneously
time-
and
challenging
to
implement.
Here,
we
review
recent
developments
time-resolved
photoemission
electron
microscopy
as
technique
study
semiconductor
nanoscale.
In
particular,
work
traditional
heterojunctions,
low-dimensional
materials,
photovoltaic
Advances in Physics X,
Год журнала:
2024,
Номер
9(1)
Опубликована: Июль 26, 2024
Excitons
–
two-particle
correlated
electron-hole
pairs
are
the
dominant
low-energy
optical
excitation
in
broad
class
of
semiconductor
materials,
which
range
from
classical
silicon
to
perovskites,
and
two-dimensional
organic
materials.
The
study
excitons
has
been
brought
on
a
new
level
detail
by
application
photoemission
momentum
microscopy
technique
that
dramatically
extended
capabilities
time-
angle
resolved
spectroscopy.
Here,
we
review
how
photoelectron
detection
scheme
enables
direct
access
energy
landscape
bright
dark
excitons,
and,
more
generally,
momentum-coordinate
exciton
wavefunction.
Focusing
materials
semiconductors,
first
discuss
typical
fingerprint
highlight
it
is
possible
obtain
information
not
only
electron-
but
also
hole-component.
Second,
focus
recent
orbital
tomography
such
this
provides
unique
real-space
properties
We
studies
performed
transition
metal
dichalcogenides
semiconductors
lead
very
similar
conclusions,
manner,
strength
for
excitations
semiconductors.
Nanophotonics,
Год журнала:
2024,
Номер
13(11), С. 1985 - 1992
Опубликована: Янв. 10, 2024
Abstract
Surface
plasmon
polaritons
(SPPs)
are
travelling
surface
waves
that
have
shown
promise
for
applications
in
nanophotonics
as
they
provide
a
direct
route
toward
photon-mediated
electrical
signal
generation
–
central
paradigm
speeding
up
and
scaling
down
photonic
elements.
SPP
also
generated
fundamental
interest
due
to
their
high-field
strength
sub-wavelength
confinement,
properties
enabled
the
surface-enhanced
Raman
effect.
Over
last
decade,
photoemission
electron
microscopy
(PEEM)
has
emerged
pioneering
technique
imaging
electric
fields
through
ultrashort
laser
pulse
mediated
emission
therefore
become
an
indispensable
tool
characterizing
plasmonic
phenomena
at
interfaces
variety
of
materials.
PEEM
offers
nanometer
spatial
resolution
femtosecond
temporal
resolution,
allowing
SPPs
be
prepared,
monitored,
manipulated
on
nanometer-femtosecond
scale.
Through
brief
review
recent
reports,
we
aim
introduce
PEEM-based
manipulation
modalities
highlight
utility
context
emerging
nanoscale
quantum
materials
science
advancements.
Nature Communications,
Год журнала:
2025,
Номер
16(1)
Опубликована: Апрель 29, 2025
As
conventional
electronic
materials
approach
their
physical
limits,
the
application
of
ultrafast
optical
fields
to
access
transient
states
matter
captures
imagination.
The
inversion
symmetry
governs
parity
selection
rule,
differentiating
between
accessible
and
inaccessible
matter.
To
circumvent
parity-forbidden
transitions,
common
practice
is
break
by
material
design
or
external
fields.
Here
we
report
how
femtosecond
ultraviolet
pulses
can
energize
a
dark
exciton
state
in
black
phosphorus
while
maintaining
its
intrinsic
symmetry.
Unlike
bandgap
absorption
visible-to-infrared,
excitation
turns
on
efficient
Coulomb
scattering,
promoting
carrier
multiplication
heating
~3000
K,
consequently
populating
states.
Interferometric
time-
angle-resolved
two-photon
photoemission
spectroscopy
reveals
dynamics
~100
fs
time
scale
anisotropic
wavefunctions
energy-momentum
space,
illuminating
potential
applications
optoelectronics
photochemistry
under
excitation.
Physical Chemistry Chemical Physics,
Год журнала:
2024,
Номер
26(15), С. 12168 - 12178
Опубликована: Янв. 1, 2024
The
generation
of
hot
carriers
(HCs)
through
the
excitation
localized
surface
plasmon
resonance
(LSPR)
in
metal
nanostructures
is
a
fascinating
phenomenon
that
fuels
both
fundamental
and
applied
research.
