Broadband single-shot transient absorption spectroscopy

Wilson, Kelly S.; Mapile, Ashley N.; Wong, C.

doi:10.1364/oe.390938

Cited by 19 publications

(18 citation statements)

References 31 publications

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“…The development of the TA spectra for ~ 1 ps is a convolution of the true ultrafast carrier relaxation dynamics and the temporal chirp of the supercontinuum probing pulse. This behavior is characteristic of sub-picosecond TA spectroscopy of semiconductors 20 and solutions of organic compounds 21 , 22 . The corresponding chirp correction result is shown as an example in Fig.…”

Section: Resultsmentioning

confidence: 82%

Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi2Se3 monitored by ultrafast transient absorption spectroscopy

Glinka

Sun

2022

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Ultrafast carrier relaxation in the 2D topological insulator (TI) Bi2Se3 [gapped Dirac surface states (SS)] and how it inherits ultrafast relaxation in the 3D TI Bi2Se3 (gapless Dirac SS) remains a challenge for developing new optoelectronic devices based on these materials. Here ultrashort (~ 100 fs) pumping pulses of ~ 340 nm wavelength (~ 3.65 eV photon energy) were applied to study ultrafast electron relaxation in the 2D TI Bi2Se3 films with a thickness of 2 and 5 quintuple layers (~ 2 and ~ 5 nm, respectively) using transient absorption (TA) spectroscopy in the ultraviolet–visible spectral region (1.65–3.9 eV). The negative and positive contributions of TA spectra were attributed to absorption bleaching that mostly occurs in the bulk states and to the inverse bremsstrahlung type free carrier absorption in the gapped Dirac SS, respectively. Owing to this direct and selective access to the bulk and surface carrier dynamics, we were able to monitor coherent longitudinal optical (LO) phonon oscillations, which were successively launched in the bulk and surface states by the front of the relaxing electron population within the LO-phonon cascade emission. We have also recognized the coherent surface-to-bulk vibrational coupling that appears through the phase-dependent amplitude variations of coherent LO-phonon oscillations. This unique behavior manifests itself predominantly for the topologically trivial insulator phase of the 2D TI Bi2Se3 (2 nm thick film) in the photon energy range (~ 2.0–2.25 eV) where efficient energy exchange between the bulk and surface states occurs. We also found that the coherent surface-to-bulk vibrational coupling significantly weakens with increasing both the Bi2Se3 film thickness and pumping power.

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Section: Resultsmentioning

confidence: 82%

Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi2Se3 monitored by ultrafast transient absorption spectroscopy

Glinka

Sun

2022

Sci Rep

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“…SSTA measurements were performed using a previously described homebuilt instrument (Wilson and Wong, 2018;Wilson et al, 2020). A 1 kHz Ti:sapphire laser (Coherent, Astrella) with an 800 nm output was used to pump an optical parametric amplifier (Light Conversion, Topas Prime Plus) to generate 520 nm pump pulses that were compressed to 50 fs using a prism pair.…”

Section: Single-shot Transient Absorptionmentioning

confidence: 99%

“…This process corrects for chirp in the broadband probe pulse. Both the wavelength and time delay calibrations are discussed in detail elsewhere (Wilson et al, 2020).…”

Section: Single-shot Transient Absorptionmentioning

confidence: 99%

“…and Wong, 2018; Wilson et al, 2020) to track the evolution of exciton dynamics in methylammonium lead triiodide (MAPbI 3 ) perovskite NCs as they nucleate and grow and as their surfaces are passivated with ligands. A complete TA spectrum with excellent signal to noise can be collected using this instrument in less than 1 min, allowing us to accurately measure immature NCs before they degrade (Sadighian et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Evolving Stark Effect During Growth of Perovskite Nanocrystals Measured Using Transient Absorption

et al. 2020

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Methylammonium lead triiodide (MAPbI 3) nanocrystals (NCs) are emerging materials for a range of optoelectronic applications. Photophysical characterization is typically limited to structurally stable NCs owing to the long timescales required for many spectroscopies, preventing the accurate measurement of NCs during growth. This is a particular challenge for non-linear spectroscopies such as transient absorption. Here we report on the use of a novel single-shot transient absorption (SSTA) spectrometer to study MAPbI 3 NCs as they grow. Comparing the transient spectra to derivatives of the linear absorbance reveals that photogenerated charge carriers become localized at surface trap states during NC growth, inducing a TA lineshape characteristic of the Stark effect. Observation of this Stark signal shows that the contribution of trapped carriers to the TA signal declines as growth continues, supporting a growth mechanism with increased surface ligation toward the end of NC growth. This work opens the door to the application of time-resolved spectroscopies to NCs in situ, during their synthesis, to provide greater insight into their growth mechanisms and the evolution of their photophysical properties.

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“…The LIF of the dye Nile Red was used to analyze the resonance effects within the LIF signal of droplets in dependence of the ethanol admixture and the droplet size. About a single-shot transient absorption spectroscope with a spatially encoded 60 ps time delay range and a 100 nm spectral range was reported in [12]. For its testing, there was used methanol solution of Cresyl Violet laser dye.…”

Section: Introductionmentioning

confidence: 99%

Spectral and emission characteristics of DCM and oxazine laser dyes in annealed silica xerogel

2021

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The solid-state laser media based on preliminary annealed xerogel SiO 2 matrices doped with three laser dyes for 600-700 nm range of tuning actively used in biomedical diagnostics and sensory analysis, were developed and studied. The spectral, fluorescence, and laser characteristics of DCM and two oxazine dyes (Ox9 and Ox17) in the solutions and the matrices were measured and analyzed. It was revealed the influence of bulky fragments able to swing within the structure of the dye molecule and its nearest neighbor surroundings on nonradiative losses in the excited S 1 state of this molecule. The specific output laser energy of DCM and Ox9 laser dyes were found to appreciably rise in the matrix as compared with their methanol solution, whereas for Ox17, this value remained approximately the same. The studied matrices had lasing in a nonselective cavity with red shift with respect to the fluorescence maximum by value of 900-1700 cm −1 . This may extend the penetration depth of laser biosensor radiation into organic tissues.

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Broadband single-shot transient absorption spectroscopy

Cited by 19 publications

References 31 publications

Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi2Se3 monitored by ultrafast transient absorption spectroscopy

Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi2Se3 monitored by ultrafast transient absorption spectroscopy

Evolving Stark Effect During Growth of Perovskite Nanocrystals Measured Using Transient Absorption

Spectral and emission characteristics of DCM and oxazine laser dyes in annealed silica xerogel

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