9 research outputs found
Seeing the vibrational breathing of a single molecule through time-resolved coherent anti-Stokes Raman scattering
The motion of chemical bonds within molecules can be observed in real time,
in the form of vibrational wavepackets prepared and interrogated through
ultrafast nonlinear spectroscopy. Such nonlinear optical measurements are
commonly performed on large ensembles of molecules, and as such, are limited to
the extent that ensemble coherence can be maintained. Here, we describe
vibrational wavepacket motion on single molecules, recorded through
time-resolved, surface-enhanced, coherent anti-Stokes Raman scattering. The
required sensitivity to detect the motion of a single molecule, under ambient
conditions, is achieved by equipping the molecule with a dipolar nano-antenna
(a gold dumbbell). In contrast with measurements in ensembles, the vibrational
coherence on a single molecule does not dephase. It develops phase fluctuations
with characteristic statistics. We present the time evolution of discretely
sampled statistical states, and highlight the unique information content in the
characteristic, early-time probability distribution function of the signal.Comment: 17 pages, 5 figure
Orientation-Dependent Handedness of Chiral Plasmons on Nanosphere Dimers: How to Turn a Right Hand into a Left Hand
Recommended from our members
SERS from the point of view of the Molecule & the Antenna
Surface Enhanced Raman Spectra (SERS) recorded on plasmonic substrate is often accompanied with broad background, origin of which is extensively deliberated. Moreover, fluctuation in the spectra is regarded as a signature of single molecule response. The plasmonic junctions typically evolve and so does the local near field, which the molecule experiences. The molecular signature indicates presence of complicated near field, as well as the background is characterized via electronic Raman of the metal. The understanding of the entire spectra is based on the molecular response, metal response and their coupling. Polarized SERS measurements on single Au or Ag nanodimer equipped with some reporter molecule shows that the emission constituting the continuum is polarized. In a metal, bulk states can only result in scattering which is unpolarized, however, the surface states of the metal can be responsible for Raman. We assign the continuua to Raman of plasmons. The polarization decomposition of the intimately related molecular and plasmonic SERS allows mechanistic assignments of the scattering process and the nature of accessible plasmons in the prototypical dumbbell antenna
Recommended from our members
Orientation-Dependent Handedness of Chiral Plasmons on Nanosphere Dimers: How to Turn a Right Hand into a Left Hand
Orientation-Dependent Handedness of Chiral Plasmons on Nanosphere Dimers: How to Turn a Right Hand into a Left Hand
Optical activity,
which is used as a discriminator of chiral enantiomers,
is demonstrated to be orientation dependent on individual, and nominally
achiral, plasmonic nanosphere dimers. Through measurements of their
giant Raman optical activity, we demonstrate that L/R-handed enantiomers
can be continuously turned into their R/L-handed mirror images without
passing through an achiral state. The primitive uniaxial multipolar
response, with demonstrable broken parity and time reversal symmetry,
reproduces the observations as resonant Raman scattering on plasmons
that carry angular momentum. The analysis underscores that chirality
does not have a quantitative continuous measure and recognizes the
manipulation of superpositions of multipolar plasmons as a paradigm
for novel optical materials with artificial magnetism
Recommended from our members
Seeing the vibrational breathing of a single molecule through time-resolved coherent anti-Stokes Raman scattering
The motion of chemical bonds within molecules can be observed in real time,
in the form of vibrational wavepackets prepared and interrogated through
ultrafast nonlinear spectroscopy. Such nonlinear optical measurements are
commonly performed on large ensembles of molecules, and as such, are limited to
the extent that ensemble coherence can be maintained. Here, we describe
vibrational wavepacket motion on single molecules, recorded through
time-resolved, surface-enhanced, coherent anti-Stokes Raman scattering. The
required sensitivity to detect the motion of a single molecule, under ambient
conditions, is achieved by equipping the molecule with a dipolar nano-antenna
(a gold dumbbell). In contrast with measurements in ensembles, the vibrational
coherence on a single molecule does not dephase. It develops phase fluctuations
with characteristic statistics. We present the time evolution of discretely
sampled statistical states, and highlight the unique information content in the
characteristic, early-time probability distribution function of the signal