Visible pump-probe spectroscopy has been used to identify and characterize short-lived metal-to-metal charge transfer (MMCT) excited states in a group of cyano-bridged mixed-valence complexes of the formula [LCo(III)NCM(II)(CN)(5)](-), where L is a pentadentate macrocyclic pentaamine (L(14)) or triamine-dithiaether (L(14S)) and M is Fe or Ru. Nanosecond pump-probe spectroscopy on frozen solutions of [L(14)Co(III)NCFe(II)(CN)(5)](-) and [L(14S)Co(III)NCFe(II)(CN)(5)](-) at 11 K enabled the construction of difference transient absorption spectra that featured a rise in absorbance in the region of 350-400 nm consistent with the generation of the ferricyanide chromophore of the photoexcited complex. The MMCT excited state of the Ru analogue [L(14)Co(III)NCRu(II)(CN)(5)](-) was too short-lived to allow its detection. Femtosecond pump-probe spectroscopy on aqueous solutions of [L(14)Co(III)NCFe(II)(CN)(5)](-) and [L(14S)Co(III)NCFe(II)(CN)(5)](-) at room temperature enabled the lifetimes of their Co(II)-Fe(III) MMCT excited states to be determined as 0.8 and 1.3 ps, respectively.
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http://dx.doi.org/10.1021/ic0506512 | DOI Listing |
We demonstrate a broadband photothermal spectroscopy in the mid-infrared region using a quantum cascade laser frequency comb operating between ∼7.7 and ∼8.2 µm covering a frequency range of ∼70 cm.
View Article and Find Full Text PDFNanoscale
January 2025
Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata-700106, India.
Herein, we investigated the carrier-phonon relaxation process in a two-dimensional (2D) BAPbBr perovskite and its heterostructure with MoS. Energy transfer was observed in the van der Waals heterostructure of 2D perovskite and monolayer MoS, leading to enhancement in the photoluminescence intensity of MoS. Femtosecond pump-probe spectroscopy was used to study the carrier and lattice dynamics of pristine 2D materials and their heterostructure.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
ECE Department, University of Wisconsin at Madison, 1415 Engineering Dr, Rm 3442, Madison, WI 53706, USA, Madison, Wisconsin, 53706, UNITED STATES.
Two-dimensional (2D) van der Waals materials are shaping the landscape of next-generation devices, offering significant technological value thanks to their unique, tunable, and layer-dependent electronic and optoelectronic properties. Time-domain spectroscopic techniques at terahertz (THz) frequencies offer noninvasive, contact-free methods for characterizing the dynamics of carriers in 2D materials. They also pave the path toward the applications of 2D materials in detection, imaging, manufacturing, and communication within the increasingly important THz frequency range.
View Article and Find Full Text PDFNano Lett
January 2025
University Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France.
Thermal transport in nanostructures plays a critical role in modern technologies. As devices shrink, techniques that can measure thermal properties at nanometer and nanosecond scales are increasingly needed to capture transient, out-of-equilibrium phenomena. We present a novel pump-probe photon-electron method within a scanning transmission electron microscope (STEM) to map temperature dynamics with unprecedented spatial and temporal resolutions.
View Article and Find Full Text PDFWe study resonance redistribution mechanisms inside a hot vapor cell. This is achieved by pumping cesium atoms on the 6S→6P resonance and subsequently probing the velocity distribution of the 6P population by a linear absorption experiment on the 6P→16S or 6P→15D transitions at 514 nm and 512 nm, respectively. We demonstrate that despite the existence of thermalization processes, traces of the initial velocity selection, imposed by the pump, survive in hyperfine levels of the intermediate (6P) state.
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