Chemical Physics femtosecond spectroscopy and microscopy laboratories @ LLC

Key laser systems and experiments

Femtosecond transient absorption laboratory (Millennia)

Laser type: Amplified Ti:Sapphire laser Solstice Ace (Spectra-Physics)
Parameter summary: 796 nm, 4 kHz repetition rate, pulse duration 60 fs, pulse energy 2 mJ.

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Millennia laboratory has a versatile transient absorption (TA) setup allowing performing time-resolved experiments in a broad spectral range (~240 – 1200 nm) with time delays from ~50 fs to 10 ns (optical delay).

Experiments:

Broad-band probe: 1380 nm from OPA (TOPAS, Light Conversion) is used for generating broad supercontinuum in CaF2 plate (370 – 1150 nm), later dispersed in a prism-based spectrograph onto a dual diode array (Pascher Instruments).

Narrow-band probe: OPA output is used directly for probing excited state dynamics of the investigated system (FWHM of ~5 – 20 nm), detected by a photodiode. The single channel detection significantly increases the signal to noise ratio of the acquired data.
Contact person: Pavel Chábera

Transient x-ray spectroscopy – part of the Millennia laboratory

Parameter summary: pump – 1 kHz repetition rate, 800nm, 400nm, or OPA (TOPAS, Light Conversion) output, probe – detector limited – 2-9 keV.

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Experiments:

Transient x-ray absorption and emission spectroscopy with sub picosecond temporal resolution. Laser generated broadband x-rays are used to probe transient states in matter. The x-rays are generated by the interaction of a high-power laser beam with a water jet, resulting in x-rays with <15 keV. The x-rays are handled in a compact setup and can be re-focused with a poly-capillary lens. The x-radiation is detected with a cryogenic microcalorimetric array that can detect 300 – 9000 eV photons. Typical measurements are pump-probe studies of light-induced charge dynamics in metalorganic compounds or nanostructures.

Contact person: Jens Uhlig

High-power THz spectroscopy – part of the Millennia laboratory

Parameter summary: 5 kHz, 800 nm, 70 fs, 1 mJ (at 800 nm)

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Experiments:

Ultrafast photoconductivity dynamics; THz spectroscopy The system for high-power VIS pump/THz probe technique. The single shot detection allows a broadband THz measurement.

Contact person: Arkady Yartsev

The femtosecond laboratory Ultra

Laser type:

(1) Amplified Ti:Sapphire laser CPA-2001 (Clark-MXR)
(2) Amplified Yb medium laser Pharos (Light Conversion)
Parameter summary:
(1) 775 nm, 1 kHz, 1.1 mJ, followed by three NOPAs: 10 ÷ 100 fs; 250 ÷ 1100 nm; up to 30 µJ.
(2) 1030 nm, 10 ÷ 600 kHz; up to 0.8 mJ (at 10 kHz), followed by two NOPAs: 20 ÷ 100 fs; 300 ÷ 950 nm; up to 5 µJ.

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Millennia laboratory has a versatile transient absorption (TA) setup allowing performing time-resolved experiments in a broad spectral range (~240 – 1200 nm) with time delays from ~50 fs to 10 ns (optical delay).

Experiments:

Transient transmission/reflection with resolution down to 10 fs. Broadband and “single colour” detection. Low level of noise: 3×10-5 OD for a pair of two pulses (with- and without- Pump). Anisotropy/Magic angle; Pump ̶ Dump/re-Pump ̶ Probe. Pulse Shaping (Coherent Control).

Contact person: Arkady Yartsev

The multidimensional spectroscopy laboratory

Laser type: 200 kHz amplified Yb medium laser (Pharos, Light Conversion) pumping two NOPAs.
Parameter summary: Sub-15 fs pulses at 470 – 970 nm, 0.5 µJ. Achromatic second harmonic generation of NOPA, providing sub-10 fs pulses, at 240 – 320 nm, 50 nJ.

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Experiments:

In 2DES excitation and detection energy resolved signals are recorded revealing correlations between optical transitions, as well as evolution of excitation and charge carrier dynamics with ~15 fs resolution.
TR-PEEM allows time (~10 fs) spatially (~40 nm) resolved imaging of exciton and charge carrier dynamics in materials at the surface. Here VIS/NIR pulses provide excitation and deep UV pulses are used for photoionization

Contact person: Donatas Zigmantas

Phase modulation ultrafast spectroscopy laboratory

Laser type: Mirror-dispersion-controlled Synergy Ti:Sapphire oscillator (Spectra-Physics).
Parameter summary: Repetition rate 70 MHz. The laser wavelength is centred at 790 nm with FWHM of 115 nm allowing laser pulse of about 8 fs with the energy of 14 nJ.

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The main experimental setup allows action-detected 2D spectroscopy experiments based on measuring fluorescence and/or photocurrent signals (2DFS and 2DPS). Even other modulation-based measurements combined with imaging can be carried out.

Experiments:

Coherent two-dimensional fluorescence and photocurrent spectroscopy (2DFS or 2DPS).

Contact person: Tönu Pullerits

High repetition rate femtosecond laboratory

Laser type: Ti:Sapphire oscillator.
Parameter summary: Output parameters: 80 MHz, 750÷1000 nm, 80 fs, 19 nJ @ 800 nm, 250-540 nm via second and third harmonic generation.

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Experiments:

  • Time-resolved photoluminescence: temporal resolution >2 ps by streak camera (Hamamatsu); available spatial resolution down to sub-micrometre by the combining of the streak camera and an optical microscope.
  • High repetition rate THz system: (time-domain) absorption and emission THz spectroscopy; time-resolved transmission THz spectroscopy. Mostly used for ultrafast photoconductivity dynamics measurements.

Contact person: Arkady Yartsev

Single molecule spectroscopy laboratory

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  • Equipment: Single Molecule Spectroscopy laboratory (SMS lab) is equipped with three wide-field fluorescence microscopes allowing for luminescence imaging and spectroscopy of any sample from a single molecule/particle to solutions and thin films. Samples can be studied in the chosen gas atmosphere, in vacuum, as well as at cryogenic temperatures. CW and pulse excitation lasers sources available over the full visible and NIR spectrum, including Super-Continuum fiber tunable-wavelength laser.
  • Experiments: Luminescence images and spectra are detected by EM CCD cameras while time-resolved emission equipment allows for luminescence decay and photon correlation measurements with 100 ps time resolution. One microscope is specially built for 2-dimentional polarization imaging (2D POLIM) developed in the lab.

Contact person: Ivan Scheblykin