This letter reports a straightforward means of collecting two-dimensional electronic (2D-E) spectra using optical tools common to many research groups involved in ultrafast spectroscopy and quantum control. In our method femtosecond pulse shaper is used generate pair phase stable collinear laser pulses which are then incident on gas or liquid sample. The followed by an ultrashort probe that spectrally resolved. delay between the incremented amplitude shaping 2D-E spectrum generated following...

We have developed a pump-probe microscope capable of exciting single semiconductor nanostructure in one location and probing it another with both high spatial temporal resolution. Experiments performed on Si nanowires enable direct visualization the charge cloud produced by photoexcitation at localized spot as spreads along nanowire axis. The time-resolved images show clear evidence rapid diffusional spreading recombination free carriers, which is consistent ambipolar diffusion surface...

To date, spectroscopic characterization of porphyrin-based metal organic frameworks (MOFs) has relied almost exclusively on ensemble techniques, which provide only structurally averaged insight into the functional properties these promising photochemical platforms. This work employs time-resolved pump-probe microscopy to probe ultrafast dynamics in PCN-222 MOF single crystals. The simultaneous high spatial and temporal resolution technique enables correlation observables both inter-...

Polycrystalline tetracene films have been explored using weak ∼ 30 fs visible laser pulses that excite the lowest singlet exciton as well coherent vibrational motion. Transient difference spectra show a triplet absorption which arises following fission (SF) and persists for 1.6 ns without decay. Adaptive pulse shaping identifies multipulse optimal fields maximize this feature by 20%. These are comprised of subpulses separated time delays correlated with period lattice vibrations suggesting...

Si nanowires (NWs) have been widely explored as a platform for photonic and electronic technologies. Here, we report bottom-up method to break the conventional "wire" symmetry synthetically encode high-resolution array of arbitrary shapes, including nanorods, sinusoids, bowties, tapers, nanogaps, gratings, along NW growth axis. Rapid modulation phosphorus doping combined with selective wet-chemical etching enabled morphological features small 10 nm be patterned over wires more than 50 μm in...

Interfacial electron transfer at titanium dioxide (TiO2) is investigated for a series of surface bound ruthenium-polypyridyl dyes whose metal-to-ligand charge-transfer state (MLCT) energetics are tuned through chemical modification. The 12 complexes the form Ru(II)(bpy-A)(L)2(2+), where bpy-A bipyridine ligand functionalized with phosphonate groups attachment to TiO2. Functionalization ancillary ligands (L) enables potential excited Ru(III/)* couple, E(+/)*, in 0.1 M perchloric acid...

While organometal halide perovskites are promising for a variety of optoelectronic applications, the morphological and compositional defects introduced by solution processing techniques have hindered efforts at understanding their fundamental properties. To provide detailed picture intrinsic carrier transport properties methylammonium lead iodide without contributions from such as grain boundaries, we utilized pump-probe microscopy to measure diffusion in individual crystalline domains thin...

Ultrafast charge carrier dynamics in silicon nanowires (NWs) grown by a vapor–liquid–solid mechanism were interrogated with optical pump–probe microscopy. The high time and spatial resolutions achieved the experiments provide insight into of single nanostructures. Individual NWs excited femtosecond pump pulse focused to diffraction-limited spot, producing photogenerated carriers (electrons holes) localized region structure. Photoexcited undergo both electron–hole recombination diffusional...

Silicon nanowires incorporating p-type/n-type (p-n) junctions have been introduced as basic building blocks for future nanoscale electronic components. Controlling charge flow through these doped nanostructures is central to their function, yet our understanding of this process inferred from measurements that average over entire structures or integrate long times. Here, we used femtosecond pump-probe microscopy directly image the dynamics photogenerated carriers in silicon encoded with p-n...

Imaging excited-state dynamics in complex materials provides an important avenue for understanding the role played by micro- and nanoscale structural compositional heterogeneity performance of active electronic optoelectronic devices. Here, we develop structured pump–probe microscopy (SPPM), a subdiffraction-limited, time-resolved that incorporates focused diffraction-limited probe field together with spatially modulated pump excitation field. We apply technique to study free carrier silicon...

Lead halide perovskites have gained attention for their potential in optoelectronic applications, including photovoltaics and light-emitting devices, due to remarkable optical electronic properties. However, performance of these materials is highly dependent on morphological properties the underlying substrates. In this study, effects substrate modifications photoluminescence lifetimes CsPbBr₃ deposited TiO2 substrates that were annealed at various temperatures investigated. characterized...

While significant research efforts directed toward characterizing the excited-state dynamics of lead halide perovskites have enabled promising advances in photovoltaic, light-emitting diode, and laser technologies, a detailed correlation between composition functionality this class materials remains unestablished. We use pump–probe microscopy to characterize both transport relaxation individual crystals CsPbI2Br, mixed halide, all-inorganic analogue well-studied organic–inorganic hybrid...

Strain-induced changes to the electronic structure of nanoscale materials provide a promising avenue for expanding optoelectronic functionality semiconductor nanostructures in device applications. Here we use pump–probe microscopy with femtosecond temporal resolution and submicron spatial characterize charge–carrier recombination transport dynamics silicon nanowires (NWs) locally strained by bending deformation. The electron–hole rate increases strain values above threshold ∼1% and, highly...

Using a variety of steady state and time-resolved microscopies, this work directly compares the excited dynamics two distinct morphologies hierarchical perylene diimide material: kinetically trapped 1D mesoscale aggregate produced with redox-assisted self-assembly process, thin film via conventional solution-processing techniques. Although constituent monomer is identical for both materials, linear dichroism studies indicate that structures possess significantly higher long-range order than...

While carrier mobility is a practical and commonly cited measure of transport, it conflates the effects two more fundamental material properties: effective mass mean scattering time charge carriers. This Letter describes correlation ultrafast imaging techniques to disentangle effect each on transport in lead halide perovskites. Two materials are compared: methylammonium tri-iodide (MAPbI3) cesium bromide diiodide (CsPbBrI2). By correlating photoinduced changes refractive index with direct...

This Letter describes the synthesis and photophysical characterization of a Ru(II) assembly consisting metal polypyridyl complexes linked together by polyfluorene scaffold. Unlike many scaffolds incorporating saturated linkages, conjugated polymer in this system acts as functional light-harvesting component. Conformational disorder breaks conjugation backbone, resulting chain composed chromophore units, whose relative energies depend on segment lengths. Photoexcitation femtosecond laser...

Structural and functional heterogeneity is a consequence of the weak noncovalent interactions that direct formation organic materials from solution precursors. While covalent tethering solution-phase assemblies provides compelling strategy to enhance intermolecular order, effects this on formed solid-state remain unestablished. This work uses pump–probe microscopy compare excited-state dynamics in thin films fabricated tethered perylene bisimide those assemblies. On average, exhibit faster...

Energy transfer along a nonconjugated polymer chain is studied with polystyrene-based copolymer of oligo(phenylene-ethynylene) (OPE) donor and thiophene-benzothiadiazole (TBT) acceptor pendants. The graft copolymers are prepared from reversible addition-fragmentation polymerization (RAFT) copper(I)-catalyzed azide-alkyne "click" reaction. singlet energy to accept via fluorescence emission ultrafast transient absorption spectroscopy. Near unity quenching the OPE excited state by TBT moiety...

A Raman-pump frequency modulation scheme and an automated signal-processing algorithm are developed for improved collection of time-resolved femtosecond stimulated Raman spectra. Together, these two advancements remove the broad background signals endemic to FSRS measurements retrieve with high sensitivity. We apply this frequency-modulated spectroscopy (FM-FSRS) characterization ultrafast energy transport in a copolymer comprised polystyrene linked oligo(phenylene–ethynylene) donor...

A light-harvesting macromolecular assembly (PT-Ru) consisting of a poly(3-hexylthiophene) (P3HT) scaffold and pendant Ru(II) polypyridyl complexes that exhibits rapid efficient formation long-lived charge-separated state is described here. Photoinduced electron transfer from the polymer backbone to was investigated by femtosecond transient absorption spectroscopy. Photoexcitation at 388 nm results in excitation both complexes, with relative probabilities 60 40%, respectively. The dominant...

Pump-probe microscopy has recently emerged as an important tool for characterizing the effects of nanoscale chemical and compositional heterogeneity on optoelectronic properties material systems. This article describes development broadband pump-probe microscopy, which utilizes a high-speed line camera high repetition rate amplified fiber laser to collect full transient spectra at 30+ kHz with sub 100 fs temporal resolution. The imaging spectroscopic capabilities technique are demonstrated...

Surface-bound, perylenediimide (PDI)-based molecular assemblies have been synthesized on nanocrystalline TiO2 by reaction of a dianhydride with surface-bound aniline and succinimide bonding. In second step, the Fe(II) polypyridyl complex [FeII(tpy-PhNH2)2]2+ was added to outside film, also Ultrafast transient absorption measurements in 0.1 M HClO4 reveal that electron injection into 1PDI* does not occur, but rather leads ultrafast formation redox-separated pair PDI•+,PDI•–, which decays...

Ultrafast carrier dynamics in silicon nanowires with average diameters of 40, 50, 60, and 100 nm were studied transient absorption spectroscopy. After 388 photoexcitation near the direct band gap silicon, broadband spectra from 400 to 800 collected between 200 fs 1.3 ns. The exhibited both absorptive bleach features that evolved on multiple time scales, reflecting contributions thermalization recombination as well shifts ground-state spectrum. initially formed "hot" carriers relaxed edge...