It is helpful if those interested first contact the local scientists at LaserLaB Amsterdam to discuss the opportunities, possibilities and limitations of the equipment. Below the access facilities are described and local contact persons indicated.
The phase-controlled parametric amplifier TeraWatt laser system
Experiments can be berformed with an ultrafast laser system based on non-collinear parametric amplification (NOPCPA) of pulses from a frequency comb laser. This combination provides unique possibilities for generating ultrashort pulses (down to 7.6 fs have been achieved), with up to 3 TW peak intensity, and with control over the carrier-envelope phase of the pulses. The system runs currently at 30 Hz repetition rate, and is combined with a high-harmonic generation setup to perform experiments in the extreme ultraviolet. Full control over the electromagnetic wave is possible because the setup also contains a phase-shaper for the full bandwidth of the system (~720 nm to 1040 nm). Diagnostics of the pulses is available in the form of e.g. a SPIDER setup, an autocorrelator, and carrier-envelope phase measurement.
Since one year the system has been extended with the possibility to generate high-power pulse-pairs (~2.5 mJ/pulse after compression in TEM00, currently with 6.6 ns time separation), with an extremely accurate phase relationship between them on the 10 mrad level. The bandwidth is reduced (<100 nm) and adjustable. In combination with the high harmonic generation, phase-coherent pulse-pairs can be generated in the extreme ultraviolet for pump-probe experiments, or for high-resolution Ramsey-type spectroscopy. Currently an experiment in helium is performed at 51 nm using 200 fs pulses, but it is expected that the system can generate coherent pulse pairs over a range of 10-1000 nm.
Contactperson: Kjeld Eikema
The narrowband tunable tunable pulsed dye amplifier setup
A Pulsed-Dye Amplifier laser system can be used for a variety of experiments, from cavity ring-down, resonance enhanced multi-photon ionization and laser-induced fluorescence detection. The system is injection seeded by the output of a continuous-wave ring dye lasers tunable in the range 560 - 660 nm. The PDA then consists of three stages of traveling wave light amplification delivering powerful pules (up to 100 mJ) in 5-6 nanoseconds with a bandwidth of ~ 80 MHz. Options for frequency doubling to the wavelength range 280 - 330 nm as well as frequency-tripling to 200 - 220 nm are available. Precision wavelength calibration ca be performed by measuring a reference spectrum of saturated iodine absorption or by a WS-& accurate wavelenngth meter
Contactperson: Wim Ubachs
Time-resolved visible pump/mid-IR probe setup
A Ti:-sapphire amplified laser system operating at 1 kHz (Hurricane, Spectra-Physics) in combination with a collinear optical parametric amplifier of superfluorescence (TOPAS, Light Conversion, Vilnius, Lithuania) and a home-built noncollinear OPA provide excitation pulses tunable between ~ 300 nm and 900 nm and probe pulses tunable between 3500 nm and 800 cm-1. The probe pulses, having a spectral width of ~180 cm-1, are dispersed in a spectrograph and imaged onto a 32-element array of MCT detectors. The cross correlation between pump and probe pulses is 150-180 fs, a delay line provides the opportunity to vary the delay between pump and probe to up to 6 ns. The setup is excellently suited for experiments on proteins, since a Lissajous sample scanner is available that provides a fresh sample shot for each laser shot, but returns to the same position after ~2 minutes. Typically in 1 minute of data collection the noise level in a single spectrum is 10-5 OD, implying a noise level of 30 micro-OD for a full data set in a few hours. There is also the possibility to simultaneously measure the absorption changes in the visible part of the spectrum. A more elaborate description of the capabilities of the setup can be found in (Photochem. Photobiol. Sci., 2007, 6, 501 : Femtosecond time-resolved and dispersed infrared spectroscopy on proteins). For experiments in the midIR on longer time scales a step-scan and rapid scan FTIR setup (Bruker), with a 6-ns OPO laser source, is available.
Contactperson: Marloes Groot
Multi-pulse ultrafast transient absorption spectrometer
With multi-pulse control spectroscopy, the course of light-induced molecular events is ‘controlled’ by applying additional stimuli at well-defined moments during the reaction. The power of the multi-pulse method lies in the ability to use a second laser pulse (or third, etc.) to selectively remove or transfer population of a transient reaction species with carefully timed and color-adjusted laser pulses, thus disentangling complex elementary events in physics, chemistry and biology.
The Multi-pulse ultrafast transient absorption spectrometer involves an amplified Ti:sapphire laser system (broadband Vitesse-short-pulse Legend, Coherent, Mountain View) of 45 fs pulse duration and 2.5 W output power operating at 1 kHz, equipped with three independently tunable, computer-controlled OPAs (Coherent OperA). Two OPA's have a visible-near IR output for tunable excitation from 475 nm to 2 micron ensuring the wide tunability of its pump and control pulses. Detection takes place with a white light continuum in a multichannel fashion on a shot-to-shot readout basis. A third OPA provides a mid-IR output which will enable the detection of spectral changes in the mid-infrared to selectively probe the dynamic structure of (bio)molecules. This facility will be installed in the near future.
In addition, a novel ultrafast vibrational technique called femtosecond stimulated Raman spectroscopy (FSRS) has been implemented in the multi-pulse setup. In ‘classical’ time-resolved Raman experiments, where two optical pulses are used, the time-resolution is always limited to a few picoseconds since otherwise the spectral resolution would be too low to resolve the individual vibrational frequencies. With FSRS this problem is overcome by using three pulses. A femtosecond excitation pulse is used to excite the sample, stimulated Raman scattering is induced by a narrow-bandwidth pulse of picosecond duration and probed by a short, broad-bandwidth white-light continuum pulse. The time-resolution in this experiment is determined by the duration of the first pulse and the probe pulse. The spectral resolution is determined by the Raman pump pulse. resulting in temporal and spectral resolutions of 100 fs and <10 cm-1 respectively. To perform FSRS, the Multi-pulse ultrafast transient absorption spectrometer has been equipped with a narrowband Second Harmonic Bandwidth Compressor (SHBC) in combination with a picosecond OPA (TOPAS, both by Light Conversion, Vilnius ) to provide tunable Raman excitation.
Contactperson: John Kennis
The ultra-narrowband pulsed Ti:Sa setup with deep-UV extensions
A Narrowband Pulsed Titanium-Sapphire oscillator amplifier has been developed for precision spectroscopic experiments. The injection seeded laser system (either by a diode laser or by a CW titanium-sapphire laser) is based on gain-switching and delivers pulses of duration up to 40 ns with Fourier-transform limited bandwidth. The layout of the oscillator (picture on the ledt), including the arrangement for on-line chirp analysis of each laser pulse at a 10 Hz repetition rate.
The output of the oscillator is amplified in a bowtie amplifier (picture on the right) with up to 9 passes delivering 30 mJ laser pulses tunable over a range 770-850 nm. These pulses as well as the frequency-coubled, tripled and quadrupled pulses (reaching the deep-ultraviolet wavelength range) can be used for high-precision spectroscopic studies. Frequency-stabilized etalons, an accurate ATOS wavelength meter, and a fiber-link to the frequency comb laser are available for absolute frequency calibration. Particularly the deep-UV options are novel tools for spectroscopic applications
Contactperson: Wim Ubachs
The frequency comb setup for absolute frequency metrology experiments
The frequency comb facility allows optical precision frequency measurements with an accuracy (at the moment) of 12 digits. Two single mode fibers link the frequency combs with other labs for remote measurement of laser frequencies. There are two types of frequency comb lasers available for this purpose. One is based on a home-built Ti:sapphire modelocked laser. It can operate from 700 nm - 900 nm (and from 350 nm to 450 nm with freequency doubling), and has a tunable repetition rate between 70 MHz - 300 MHz. The other system is a commercial (Menlo-systems) one based on Er-fiber technology. It operates at a repetition rate of 250 MHz. With this system precision calibration can take place from 550 - 2000 nm. Both frequency comb lasers are locked to a Rubidium atomic clock, which itself is locked to the GPS system for long term stability and accuracy.
Contacteprson: Kjeld Eikema
The gas phase cavity-ring down facility
The cavity ring-down technqiue can be used to measure weak transitions of molecules in the gas phase, or probe trace gases, or low-abundant isotopic species. At LCVU several setups are available to perform such studies over a wide wavelength range. Pulsed tunable lasers are avaliable, covering the entire wavelength range between 200 and 900 nm to be employed in gas-phase CRD; similarly a wide range of CRD-mirrors with highly reflective coatings is available.
A special cell has been designed to perfrom so-called pressure ramp CRD studies to extract low extinction cross sections, such as e.g. the Rayleigh cross section. The cell exhibits arrays of inlet holes to allow for turbulance-free pressure ramping a cell up to pressure of 1 Bar.
In addition to pressure ramps and static gas measurements we have als available a slit-discharge nozzle setup to perform CRD-absorption measurements along a slit, where the discharge provides the formation of short-lived radical species and ions in the gas phase.
Contactperson: Wim Ubachs
Setup for video-microscopy of biological molecular motors
The set-up consists of an inverted optical microscope (Olympus IX70) equipped with a CCD camera (Dage-MTI) and a temperature-controlled (5- 80oC, Linkam) stage for investigation of biological specimen.
Biological motors (in our laboratory the rotary molecular motor F1-ATPase), labeled via affinity tags (e.g. biotin, streptavidin) with large probes such as micro- and nano-beads, are immobilized on slide glasses and observed in real time. Motor movement is analyzed by custom-made software in terms of motor speed, torque, pauses, or dwell times in response to experimental parameters (temperature, source and stability of motor, substrate or inhibitor concentration).
Contactperson: Dirk Bald
Doppler Electrophoretic Light Scattering Analyzer
The Coulter Delsa 440 measures distribution of electrophoretic mobility and zeta potentials of particles and colloids (0.02 - 30 mm diameter) in liquid suspension using laser Doppler velocimetry. The system comprises an optical bench with a helium-neon laser, a sample chamber, a frequency shifter, a 24fold magnification microscope and four photodiode detectors. The beam is spilt into main beam and four reference beams that detect scattered light at four angles. The main beam's frequency is changed by a controlled amount in a frequency shifter, allowing for detection of particle mobility and (surface) properties. This set-up can be used for analysis of nano-particles carrying (multiple) biological surface layers, such as receptors or DNA, which may allow usage of these particles for detection or diagnostics.
Contactperson: Dirk Bald
Facility for combined optical trapping, single-molecule fluorescence and microfluidics experiments on DNA
We designed and built an optical-tweezers instrument that allows manipulation of two DNA molecules in three dimensions simultaneously and independently by trapping micrometer-sized polystyrene beads attached to the ends of the DNA molecules. Four optical traps are generated by first splitting a laser beam in two orthogonally polarized beams. One of these beams generates a continuous trap; the other beam is time-shared over three trap positions using acousto-optic deflectors. Forces acting on the bead in the continuous trap can be detected with subpicoNewton resolution using back-focal-plane interferometry. To attach DNA between the four beads held in the optical traps, we have previously designed and constructed a flow chamber with multiple laminar flows of solution running parallel to each other. By moving the chamber relative to the optical traps, the four trapped beads can be moved into different solutions.
Contact person: Gijs Wuite
Microscope for wide-field, single-molecule fluorescence imaging
This custom-designed instrument allows for epi- and through-the objective TIRF illuminated wide-field fluorescence excitation. Light is provided by 488, 532, 576 and
635 nm CW lasers. Wavelengths can be switched using a acousto-optical tunable filter. Images are collected using a back-illuminated EMCCD. The instrument is set up for simultaneous detection of two of three different spectral channels. Optical filters are available for detection of EGFP/fluorescein/Alexa 488, Cy3/Alexa 555, mCherrry/Texas Red and Cy5/Alexa 647. The instrument was designed in particular for in vitro motility assays using kinesin and other motor proteins and imaging of single fluorophores in living cells.
Contactperson: Erwin Peterman
Confocal microscope for single-molecule fluorescence spectroscopy
This instruments, based on an inverted microscope, allows for confocal fluorescence excitation using by 488, 532, 576 and 635 nm CW lasers. Fluorescence can be split in two spectral (or polarization) channels and is detected by avalanche photodiodes. The pulses arising from the APDs are counted, time tagged (with 12.5 ns resolution) and processed using a fast counting board. Software for further processing (auto / cross correlations, time binning) is available. The sample can be moved using a 3-dimensional piezo stage. The instrument was designed for confocal motility assays using labeled kinesin and other motor proteins.
Contactperson: Erwin Peterman
Facility for optical trapping of multiple DNA molecules in combination with microfluidics
This instrument is built around an inverted optical microscope and designed for experiments on DNA with lengths ranging from ~2 to 20 micron. It consists of three modalities. (i) The sample is contained in a multichannel microfluidic flow cell, which allows for rapid buffer exchange. (ii) It employs two independently steerable optical traps (1064 nm, 3 Watt total power). One of the traps can be moved actuated via computer control. Force / displacement is measured by means of a position-sensitive detector and read out using a 24 bit ADC board. Force feedback is available for force-clamp measurements on the ~10 Hz time scale. (iii) Fluorescence arising from proteins or labels bound to the DNA can be detected, with single-fluorophore accuracy. Excitation light is provided by 473 nm, 532 nm and 633 nm continuous-wave lasers (powers up to 25 mW). Fluorescence images are detected using an EMCCD camera. Optical filters are available for detection of EGFP/fluorescein/Alexa 488, Cy3/Alexa 555, and Cy5/Alexa 647.
Contactperson: Erwin Peterman & Gijs Wuite
Atomic Force Microscope designed for high resolution biological imaging
We operate a Nanotec Atomic Force Microscope (Madrid) which incorporates ‘‘jumping mode’’ imaging. The relevant feature of this mode is that the lateral displacement of the tip occurs always when it is not in contact with the sample so that shear forces are avoided. During imaging with jumping mode, the tip performs a rapid succession of force–distance (FZ) curves, each taken in several milliseconds in a raster scanning fashion. The maximal applied force is well defined because each individual approach is stopped at the cantilever deflection corresponding to the set force. FZ curves were recorded by measuring cantilever deflection (force) as a function of the vertical position of the piezo to which the sample was mounted. The experiments can be performed in liquid using this setup.
Contactperson: Gijs Wuite