Azobenzene – functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers

Pavlenko, E. S.; Sander, M.; Mitzscherling, Steffen; Pudell, J.; Zamponi, F.; Rössle, Matthias; Bojahr, André; Bargheer, Matias

doi:10.1039/c6nr01448h

Cited by 9 publications

(16 citation statements)

References 41 publications

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“…In order to observe the effect of the molecular strain actuation itself, we excited sample 1*, i.e., sample 1 without GNRs, with 398 nm pump-pulses to launch ultrafast strain waves. The PAzo/PAH layer strongly absorbed the pump light and subsequently expanded, starting at the interface between PAzo/PAH and PSS/PAH, 11 very similar to previous experiments in layered solids. 51 The expansion wave traveled through PAzo/PAH toward the substrate, while the concomitant compression wave propagated through PSS/ PAH toward the surface (Figure 1).…”

Section: ■ Resultssupporting

confidence: 86%

“…These two spectral signatures originating from the hyper-sound-wave in the PAzo/ PAH transducer were observed in all samples with PAzo/PAH layers that are thick enough to host more than one oscillation period. 11 From the TDBS oscillations analysis, the sound velocity in the polyelectrolyte layers is calculated to be ν poly = 3.4 nm/ps. 11 The blue-shift of the thin-film interference observed throughout the entire spectrum in sample 1* (Figure 2b) is still visible after the deposition of GNR (sample 1, Figure 2c, dark arrow).…”

Section: ■ Resultsmentioning

confidence: 99%

“…6−9 Only recently, azobenzene containing polymers were introduced as photoacoustic transducers of hyper-sound-waves with wavelengths in the nanometer range, enabling time-domain Brillouin scattering in soft matter. 10,11 The viscoelastic response of tissues and polymers has been measured by spontaneous Brillouin scattering, 12,13 and recent progress is aimed at threedimensional microscopy of elasticity. 14 Hyper-sound-waves produced in a platinum transducer have recently been exploited for measuring the stiffness of nanocontacts in disordered particle assemblies 15,16,16,17 and for opto-acoustic metrology of nanoporous films.…”

Section: ■ Introductionmentioning

confidence: 99%

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Gold Nanorods Sense the Ultrafast Viscoelastic Deformation of Polymers upon Molecular Strain Actuation

et al. 2016

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On the basis of the layer-by-layer deposition of polyelectrolytes, we have designed hybrid nanolayer composites for integrated optoacoustic experiments. The femtosecond-laser-excitation of an Azo-functionalized film launches nanoscale strain waves at GHz frequencies into a transparent polymer layer. Gold nanorods deposited on the surface sense the arrival of these hyper-sound-waves on the picosecond time scale via a modification of their longitudinal plasmon resonance. We simulated the strain waves using a simple linear masses-and-springs model, which yields good agreement with the observed time scales associated with the nanolayer thicknesses of the constituent materials. From systematic experiments with calibrated strain amplitudes we conclude that reversible viscoelastic deformations of the polyelectrolyte multilayers are triggered by ultrashort pressure transients of about 4 MPa. Our experiments show that strain-mediated interactions in nanoarchitectures composed of molecular photoswitches and plasmonic particles may be used to design new functionalities. The approach combines the highly flexible and cost-effective preparation of polyelectrolyte multilayers with ultrafast molecular strain actuation and plasmonic sensing. Although we use simple flat layered structures for demonstration, this new concept can be used for three-dimensional nanoassemblies with different functionalities. The ultrafast and reversible nature of the response is highly desirable, and the short wavelength associated with the high frequency of the hyper-sound-waves connecting photoactive molecules and nanoparticles inherently gives spectroscopic access to the nanoscale. High-frequency elastic moduli are derived from the ultrafast spectroscopy of the hypersonic response in polyelectrolyte multilayers.

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Section: ■ Resultssupporting

confidence: 86%

Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Gold Nanorods Sense the Ultrafast Viscoelastic Deformation of Polymers upon Molecular Strain Actuation

et al. 2016

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“…Opto-acoustic transducers that enable efficient coupling between photons and acoustic phonons are important in a number of emerging applications, including as the active elements in phonon lasers, − and for imaging the mechanical properties of soft matter systems. − In imaging experiments time domain measurements are typically used, where femtosecond laser pulses generate and detect the propagating acoustic waves. − In these experiments the pump laser generates a transient stress in the sample, that launches acoustic waves into the surroundings. Reflection of the probe laser from the traveling wavefront creates an interference, which gives an oscillation in the transient reflectivity signal.…”

mentioning

confidence: 99%

Brillouin Oscillations from Single Au Nanoplate Opto-Acoustic Transducers

Devkota

Beane

et al. 2017

ACS Nano

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Brillouin oscillations, which are GHz frequency waves that arise from the interaction of light with acoustic waves, are experiencing increasing applications in biology and materials science. They provide information about the speed of sound and refractive index of the material they propagate in, and have recently been used in imaging applications. In the current study, Brillouin oscillations are observed through ultrafast transient reflectivity measurements using chemically synthesized Au nanoplates as opto-acoustic transducers. The Au nanoplates are semitransparent, which allows the Brillouin oscillations to be observed from material on both sides of the plate. The measured frequencies are consistent with the values expected from the speeds of sound in the different materials, however, the attenuation constants are much larger than those reported in previous studies. The increased damping is attributed to diffraction of the acoustic wave as it propagates away from the excitation region. This effect is more significant for experiments with high numerical aperture objectives. These results are important for understanding the relationship between frequency and spatial resolution in Brillouin oscillation microscopy.

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“…58,59 Pronounced phase jumps in this Brillouin signal occur when the strain pulses invert their sign due to the reflection at the SiO 2 /air interface. 55,60 Consequently, the strain propagation as modeled by the 1D-linear chain model accurately predicts the timings of all the experimental signals we observed in this heterostructure. We have employed a single temperature model for the driving stress on the lattice.…”

Section: B) Signals In the Sio 2 Capped Samplementioning

confidence: 65%

Tracking picosecond strain pulses in heterostructures that exhibit giant magnetostriction

Zeuschner

Parpiiev

Pézeril

et al. 2019

Structural Dynamics

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We combine ultrafast X-ray diffraction (UXRD) and time-resolved Magneto-Optical Kerr Effect (MOKE) measurements to monitor the strain pulses in laser-excited TbFe 2 /Nb heterostructures. Spatial separation of the Nb detection layer from the laser excitation region allows for a background-free characterization of the laser-generated strain pulses. We clearly observe symmetric bipolar strain pulses if the excited TbFe 2 surface terminates the sample and a decomposition of the strain wavepacket into an asymmetric bipolar and a unipolar pulse, if a SiO 2 glass capping layer covers the excited TbFe 2 layer. The inverse magnetostriction of the temporally separated unipolar strain pulses in this sample leads to a MOKE signal that linearly depends on the strain pulse amplitude measured through UXRD. Linear chain model simulations accurately predict the timing and shape of UXRD and MOKE signals that are caused by the strain reflections from multiple interfaces in the heterostructure.

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Azobenzene – functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers

Cited by 9 publications

References 41 publications

Gold Nanorods Sense the Ultrafast Viscoelastic Deformation of Polymers upon Molecular Strain Actuation

Gold Nanorods Sense the Ultrafast Viscoelastic Deformation of Polymers upon Molecular Strain Actuation

Brillouin Oscillations from Single Au Nanoplate Opto-Acoustic Transducers

Tracking picosecond strain pulses in heterostructures that exhibit giant magnetostriction

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