Download scientific diagram femtosecond transient absorption. Materials science and technology division, oak ridge national laboratory, oak ridge, tn 37831, united states. Transient absorption microscopy of monolayer and bulk wse2, acs nano 8. Quantitative scanning transmission electron microscopy study of monolayer re xmo 1xs 2. We wish to extend this to enable the study of molecular transformations such as protein folding and dna transformation in real time. Transient absorption microscopy of gold nanorods as. Photoluminescence imaging of wse 2 monolayer essence hansberry, kevin han, prof.
Chapter 3 provides the results of the investigation of some popular laser dyes and other substances which. Transient absorption measurements on anisotropic monolayer. Ultrafast transient absorption measurements of photocarrier dynamics in monolayer and bulk rese 2. These are are approximately located at 118, 4, 164 and 212 cm1.
Ultrafast transient terahertz conductivity of monolayer mos2. Transient excitonpolariton dynamics in wse2 by ultrafast. Electric field and strain effects on the electronic and. Monolayer ml and fewlayer rese2 have been successfully. Inhomogeneous photocarrier dynamics and transport in. Quantitative scanning transmission electron microscopy study. We demonstrate broadband photocarrier generation in ws2graphene heterostructures by imaging interlayer couplingdependent charge generation using ultrafast transient absorption microscopy. Anisotropic optical and transport properties of monolayer res 2 fabricated by mechanical exfoliation are reported. Aa 0 map of monolayer ws 2 as the function of both delay time and probe photon energy with the pump photon energy of 3. Under the excitation of a 405 nm pump pulse, the differential reflection signal of a probe pulse tuned to the aexciton resonance reaches a peak rapidly that indicates. Investigation of the photoinduced dynamics of allyl systems. Aug 20, 2015 the raman spectrum of bulk wte 2 shows four main peaks in the region 100cm1 300 cm1, figure 1.
Transient absorption microscopy of monolayer and bulk wse2, acs nano 8, 2970 2014. Morphology changes of the monolayer caused by the laser pump pulse are monitored by transmission electron microscopy. Materials science and technology division, oak ridge national laboratory, oak. We recorded a photoconductivity and photoluminescence response time of just 350 fs from cvdgrown monolayer mos2, and 1 ps from trilayer mos2 and monolayer wse2. Zhao et al used transient absorption microscopy to measure the realspace exciton diffusion coefficients of excitons in bulk and monolayer wse 2 35, and journal of physics d. In this work, comprehensive temperature and excitation power dependent photoluminescence and timeresolved photoluminescence studies are carried out on monolayer wse 2 to reveal its properties of exciton emissions and related excitonic dynamics. Mar 11, 2004 femtosecond transient absorption spectroscopy is used to investigate hot electron dynamics of closepacked 6 nm gold nanocrystal monolayers. Transient absorption measurements with different polarization configurations and sample orientations reveal that the absorption coefficient and transient absorption are both anisotropic, with maximal and minimal values occurring when the light polarization is parallel and. Probing the electronic properties of bulk and monolayer crystals of tungsten dichalcogenides using magnetospectroscopy anatolie mitioglu to cite this version. Semiconductor vdw materials such as wse2 are of particular interest for photonic and quantum integrated technologies because they sustain visiblenearinfrared visnir excitonpolariton ep modes at room. Ultrafast transient absorption measurements of photocarrier.
Ultrafast characterization of saturable absorption in. Newports transient absorption spectrometer tas is a stateoftheart instrument for femtosecond pumpprobe spectroscopy. Crossref xiehong cao, zongyou yin and hua zhang, threedimensional graphene materials. Zhao et al used transient absorption microscopy to measure the realspace exciton diffusion coefficients of excitons in bulk and monolayer wse 2, and then studied the formation of excitons in monolayer wse 2, ws 2, mos 2 and mose 2. Applied physics ultrafast exciton dynamics in chemical heterogenous wse 2 monolayer fan nan1. At low pump power, the monolayer maintains its structural integrity.
Transient absorption microscopy of monolayer and bulk wse2. Thirdharmonic generation in ultrathin films of mos2, appl. The transient absorption spectrum of monolayer film mos 2 fig. Quasiparticle band structure calculation of monolayer. Ultrafast spectroscopy is an interdisciplinary area of research that spans various disciplines in chemistry and provides essential information on the mechanistic and kinetic details of chemical events that occur in. Qiannan cui, frank ceballos, nardeep kumar and hui zhao, transient absorption microscopy of monolayer and bulk wse2, acs nano, 8, 3, 2970, 2014. Zhao, transient absorption microscopy of monolayer and bulk wse2, acs nano 8, 29702976 2014.
Transient absorption white light continuum transient spectrum analyse light transient absorption spectroscopy these keywords were added by machine and not by the authors. Quasiparticle band structure calculation of monolayer, bilayer, and bulk mos 2 tawinan cheiwchanchamnangij and walter r. Preparation of monolayer mos 2 quantum dots using temporally shaped femtosecond laser ablation of bulk mos 2 targets in water bo li, lan jiang, xin li, peng ran, pei zuo, andong wang, liangti qu, yang zhao, zhihua cheng, yongfeng lu. Ultrafast exciton dynamics in chemical heterogenous wse2 monolayer. Tas incorporates newports highest quality optics, optomechanics, spectrograph, optical chopper, vibration control, delayline stage, and easytouse labview based software to deliver high quality results with. Figure 3 shows a comparison of the absorption, pl, and transient absorption spectrum obtained at a pumpprobe delay of 1 ps. Ultrafast exciton dissociation at the 2dws2 monolayer. Transient absorption spectroscopy on spiropyran monolayers. Interlayer chargetransfer ct transitions and hot carrier.
The gray line shows the pl spectrum of the monolayers sample in arbitrary units. By varying the probe wavelength using an optical parametric oscillator, we are able to reconstruct absorption spectra of intermediate states with a timeresolution of 10 nanoseconds, limited by the temporal convolution of the two. Raman spectra of monolayer, fewlayer, and bulk rese2. Influence of the substrate material on the optical properties. As the size of the wse 2 monolayer increases, the exciton emission presents nonlinear behavior and exhibits concentric fluorescence triangles with dark and bright bands in their fluorescence microscope images. Photoinduced trion absorption in the time and spectrumresolved circular dichroism cd of a pristine wse 2 monolayer is manifested by a pronounced trion transition when the circular polarization of a probe pulse is opposite to that of the preceding pump pulse. Defect correlated photocarrier dynamics are observed across the monolayer mos 2 where exciton formation and nonradiative recombination are the two dominant decay processes. Sep 21, 2014 transient absorption of gold nanorods. A setup has been constructed to measure the amount of photoluminescence found in a sample of tungsten diselenide wse. The laser systems are traditionally associated with studying ultrafast processes on macroscopic samples, in bulk solutions.
Jcm 2 and probe with the supercontinum white light at t 78 k. Ming wu abstract photoluminescence is the emission of light from a material due to photoexcitation. Epitaxial growth of a monolayer wse2mos2 lateral pn. Photoluminescence properties and exciton dynamics in. Cui q, ceballos f, kumar n and zhao h 2014 transient absorption microscopy of monolayer and bulk wse2 acs nano 8 2970. The typical optical images of monolayer and bilayer wse 2 are depicted in fig. Broadband femtosecond transient absorption spectroscopy for. We present an experimental investigation on the exciton dynamics of monolayer and bulk wse 2 samples, both of which are studied by femtosecond transient absorption microscopy. Quantitative scanning transmission electron microscopy.
Semiconductor vdw materials such as wse2 are of particular interest for photonic and quantum integrated technologies because they sustain visiblenearinfrared visnir excitonpolariton ep. Lambrecht department of physics, case western reserve university, cleveland, ohio 441067079, usa received 25 march 2012. This process is experimental and the keywords may be updated as the learning algorithm improves. Transient kinetics of the spiropyran to merocyanine conversion are recorded in a uvpump, visprobe configuration. High resolution image download ms powerpoint slide. Here we use transient absorption microscopy to isolate a unique signature of a hidden interface in a tipspentacene thin film, exposing its exciton dynamics and intermolecular structure.
Transient absorption microscopy of gold nanorods as spectrally orthogonal labels in live cells tao chen, a shouhui chen, b jihan zhou, c dehai liang, c xiaoyuan chen d and yanyi huang a. However, the absorption spectrum of gc 3 n 4 wse 2 heterostructure extends to the whole uvvis light absorption and exhibits stronger uv absorption, suggesting that the uvvis light utilization of gc 3 n 4 wse 2 heterostructure is more efficient. The isolated gc 3 n 4 monolayer only reveals a narrow uv light absorption below 400 nm. Downloaded by westfalische wilhelms universitat munster on. Charge carriers are injected by interband absorption of a 555nm pulse, and probed by measuring differential reflection of a timedelayed and spatially scanned 660nm pulse. Ultrafast exciton dynamics in chemical heterogenous wse2. Under the excitation of a 405 nm pump pulse, the differential reflection signal of a probe pulse tuned to the aexciton resonance reaches a peak rapidly that indicates an ultrafast formation process of excitons. Transient absorption microscopy of monolayer and bulk wse2, acs nano 8, 29702976 2014. Wang2 1politecnico di milano, piazza leonardoda vinci 32, i203 milan, italy 2nanjing university, nanjing 210093, china chiara. Femtosecond transient absorption dynamics of closepacked. Transient absorption microscopy of mono layer and bulk wse2.
Five pronounced pl peaks were observed from monolayer wse 2. Valleypolarized trion absorption enables visualization of the intervalley scattering dynamics of spinpolarized carriers, revealing. Transient absorption is a secondary absorption that happens after a material has been excited through primary absorption. We have performed ultrafast optical microscopy on single flakes of atomically thin cvdgrown molybdenum disulfide, using nondegenerate femtosecond pumpprobe spectroscopy to. Transient absorption microscopy of mono layer and bulk.
Femtosecond transient absorption spectroscopy is used to investigate hot electron dynamics of closepacked 6 nm gold nanocrystal monolayers. Here, femtosecond transient absorption spectroscopy and microscopy were employed to study the photocarrier dynamics and transport in monolayer mos 2. Photocarrier generation from interlayer chargetransfer. Observation of switchable photoresponse of a monolayer wse. Abdulmunem1, xing lin1, jan kuhnert1, khaleel hassoon1, saeideh edalatiboostan1, young duck kim3, wolfram heimbrodt1, euihyeok yang2, james c. Our results indicate the potential of these materials as highspeed optoelectronic materials.
Ultrafast transient absorption spectroscopy the principle of ultrafast transient absorption spectroscopy the process of energy transfer in a photosynthetic membrane typically takes place on a time scale from less than 100 fs to hundreds of ps sundstro. Mechanical exfoliation and characterization of single. The a 1 3 and a 1 4 modes becomes completely extinct in monolayer wte 2. Osa photoinduced excitonic structure renormalization and. We investigate the exciton emission and transient absorption properties in sizedependent wse 2 monolayers using photoluminescence and pumpprobe microscopy techniques.
This paper describes recent results from using transient absorption microscopy to investigate energy relaxation processes in single metal and semiconductor nanowires. This universal photophysical process exists in almost all types of nanomaterials, making it an ideal modality to monitor the location, dynamics, and interactions. Transient absorption spectroscopy of ruthenium and. The observation of absorptiontype resonances due to both neutral and charged. We have performed ultrafast optical microscopy on single flakes of atomically thin cvdgrown molybdenum disulfide, using nondegenerate femtosecond pumpprobe spectroscopy to excite and probe. Monolayer wse 2 consists of one tungsten layer sandwiched by two selenium layers as illustrated in fig. Probing the origin of excitonic states in monolayer wse 2. Probing the electronic properties of bulk and monolayer.
Different mechanisms can contribute to transient absorption. We present an experimental investigation on the exciton dynamics of monolayer and bulk wse2 samples, both of which are studied by femtosecond transient absorption microscopy. The raman spectrum of bulk wte 2 shows four main peaks in the region 100cm1 300 cm1, figure 1. Zhao, transient absorption microscopy of monolayer and bulk wse2, acs nano 8, 2970. Surprisingly, instead of finding an abrupt grain boundary, we reveal that the interface can be composed of nanoscale crystallites interleaved by a web of. Broadband femtosecond transient absorption spectroscopy. Preparation of monolayer mos2 quantum dots using temporally. Photoinduced bandgap renormalization governs the ultrafast. Probing the electronic properties of bulk and monolayer crystals of tungsten dichalcogenides using magnetospectroscopy. To investigate monolayer rese 2 and to provide characterization tools for future work, we have recorded raman spectra of bulk, fewlayer, and monolayer rese 2 there are no published raman spectra of pure rese 2 in any form though raman spectra of res 2 have been reported and there is one report of the raman scattering of modoped rese 2. Transient absorption spectroscopy of ruthenium and osmium polypyridyl complexes adsorbed onto nanocrystalline tio2 photoelectrodes darius kuciauskas, jeremy e. Determination of the time zero point temporal overlap of pump and probe pulses is a very important and sometimes not trivial task in transient absorption experiments. Ultrafast optical microscopy of single monolayer molybdenum. Pl spectra from monolayer and bulk wse 2 flakes were first measured at a temperature of t 10 k using the 488 nm cw excitation laser.
We report a transient absorption microscopy study of charge carrier dynamics in bulk mos2 crystals at room temperature. Figure 1 a schematic of the monolayer wse 2 sample. Transient absorption microscopy is an experimental technique that allows nanomaterials to be studied with ultrafast time resolution and diffraction limited spatial resolution. Osa ultrafast transient absorption measurements of. Transient absorption microscopy studies of single metal and.