Femtosecond fluorescence upconversion setup with broadband detection in the ultraviolet

Cannizzo, Andrea; Bräm, Olivier; Zgrablić, Goran; Tortschanoff, A.; Oskouei, Ahmad Ajdarzadeh; Mourik, Frank van; Chergui, Majed

doi:10.1364/ol.32.003555

Cited by 65 publications

(73 citation statements)

References 14 publications

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“…Time-resolved emission measurements were carried out by the fluorescence up-conversion technique in the ultraviolet region 40 . Briefly, a Coherent-RegA Ti:Sapphire regenerative amplifier provided 800 nm pulses of 4 mJ typical energy and 80 fs duration (full width at half maximum (FWHM) of the intensity autocorrelation curve).…”

Section: Methodsmentioning

confidence: 99%

Real-time observation of the charge transfer to solvent dynamics

et al. 2013

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Intermolecular electron-transfer reactions have a crucial role in biology, solution chemistry and electrochemistry. The first step of such reactions is the expulsion of the electron to the solvent, whose mechanism is determined by the structure and dynamical response of the latter. Here we visualize the electron transfer to water using ultrafast fluorescence spectroscopy with polychromatic detection from the ultraviolet to the visible region, upon photo-excitation of the so-called charge transfer to solvent states of aqueous iodide. The initial emission is short lived (B60 fs) and it relaxes to a broad distribution of lower-energy charge transfer to solvent states upon rearrangement of the solvent cage. This distribution reflects the inhomogeneous character of the solvent cage around iodide. Electron ejection occurs from the relaxed charge transfer to solvent states with lifetimes of 100-400 fs that increase with decreasing emission energy.

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Section: Methodsmentioning

confidence: 99%

Real-time observation of the charge transfer to solvent dynamics

et al. 2013

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“…5,20,42 Briefly, we use 290 nm pulses with a bandwidth of about 4 nm and a pulse width of about 70 fs at a repetition rate of 250 kHz. The excitation energy of 30 nJ pulse À1 was chosen to be in the linear regime of excitation.…”

Section: Methodsmentioning

confidence: 99%

“…The extension of the fluorescence up-conversion technique with broadband detection to the UV has demonstrated promising capabilities to follow vibrational relaxation in real time. 12,20 Here, we focus on the early dynamics of UV chromophores, from the end of the ultrafast intramolecular vibrational redistribution (IVR) to the complete transfer of the excess energy (heat) to the bulk solvent.…”

Section: Introductionmentioning

confidence: 99%

A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

Braem

Penfold

Cannizzo

et al. 2012

Phys. Chem. Chem. Phys.

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We present a femtosecond broad-band fluorescence up-conversion study of the vibrational relaxation dynamics of two UV chromophores, 2,5-diphenyloxazole (PPO) and para-terphenyl (pTP), pumped with a large excess of vibrational energy (42000 cm À1 ). The band narrowing of the transient fluorescence spectrum reflects a biphasic cooling process in a few hundreds of fs and a few ps. In the sub-ps regime, our data suggest a structural rearrangement in the excited state, followed by thermalization of the excess energy. These dynamics affect the fluorescence spectra of PPO and pTP in different ways. In PPO, the damping of a low frequency vibrational wavepacket and a significant sub-ps narrowing of the band characterize the vibrational relaxation. In pTP, the latter is faster and appears as a red shift with distortion of the band in o200 fs.

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“…[70]. In our experimental configuration, a 150 kHz Ti:Sapphire regenerative amplifier system (Coherent, RegA-9000) is seeded by a mode-locked continuously.…”

Section: S3 Ultrafast Broadband Fluorescence Upconversionmentioning

confidence: 99%

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

et al. 2018

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The recent identification of strongly bound excitons in room temperature anatase TiO 2 single crystals and nanoparticles underscores the importance of bulk many-body effects in samples used for applications. Here, for the first time, we unravel the interplay between many-body interactions and correlations in highly-excited anatase TiO 2 nanoparticles using ultrafast two-dimensional deepultraviolet spectroscopy. With this approach, under non-resonant excitation, we disentangle the optical nonlinearities contributing to the bleach of the lowest direct exciton peak. This allows us to clock the ultrafast timescale of the hot electron thermalization in the conduction band with unprecedented temporal resolution, which we determine to be < 50 fs, due to the strong electronphonon coupling in the material. Our findings call for the design of alternative resonant excitation schemes in photonics and nanotechnology.1 arXiv:1703.07818v2 [cond-mat.mes-hall] 13 Jan 2018In the last decades, anatase TiO 2 has attracted huge interest as one of the most promising materials for a variety of challenging applications, ranging from photocatalysis [1,2] and photovoltaics [3] to sensors [4,5]. Since these technologies involve charge transport, thermalization and localization, they call for studies of the fast electron and hole dynamics, which provide a deep knowledge of the nature of the photogenerated/injected charge carriers and of the energy balance therein. These processes intimately depend on the details of the electronic structure and the presence of many body-effects in the material. Since anatase TiO 2 is a d 0 transition metal oxide, strong electron-electron correlations do not play a substantial role in the electronic structure [6]. Hence, this solid can be classified within the simple band insulator scheme, in which the forbidden energy gap arises as a result of band theory and is not a consequence of the strong on-site Coulomb interaction. However, different to conventional band insulators, anatase TiO 2 represents a peculiar example in which electron-phonon interaction and electron-hole correlation become relatively strong and influence the optical spectra. On the one hand, the presence of a moderately large electron-phonon coupling in anatase TiO 2 has often been invoked to interpret experimental results naturally pointing to the polaronic (self-trapped) picture [7][8][9][10][11][12][13]. Notable examples include the low temperature green photoluminescence (PL) due to self-trapped excitons [14][15][16][17][18][19][20] and the room temperature electron mobilities whose values are limited by strong scattering with phonons [10]. On the other hand, many-body correlations have been thought to be negligible in this material and, as such, they remained widely unexplored. Recently, by employing state-of-the-art experimental [21] and computational techniques [21][22][23][24][25], the substantial role of electron-hole Coulomb correlations was unravelled in the anatase polymorph of TiO 2 . Strongly bound direct excitons were...

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Femtosecond fluorescence upconversion setup with broadband detection in the ultraviolet

Cited by 65 publications

References 14 publications

Real-time observation of the charge transfer to solvent dynamics

Real-time observation of the charge transfer to solvent dynamics

A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

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