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An experimental setup for Fourier transform infrared (FTIR) studies in condensed matter at high pressure and low temperatures is described. We have adapted a close-cycle cryostat (T=20–300 K) to the sample compartment, which is used as a cryo chamber, of a FTIR spectrometer (frequency range 10–15 000 cm−1). A Cassegrain-type beam condenser is assembled to measure infrared absorptions of samples contained in a membrane diamond anvil cell (P up to 100 GPa). The tuning of the pressure and the cell alignment is performed from outside the evacuated instrument. An additional light path allows visual observation and in situ pressure calibration. The advantages of this system, demonstrated by its application to CH4 and Ar–(H2)2 crystals, are high radiation throughput, long time stability, visual observation of the sample, remote measurement and variation of the local pressure, and remote alignment of the cell with the IR beam.

A comparison of different calibration methods for optical tweezers with the differential interference contrast (DIC) technique was performed to establish the uses and the advantages of each method. A detailed experimental and theoretical analysis of each method was performed with emphasis on the anisotropy involved in the DIC technique and the noise components in the detection. Finally, a time of flight method that permits the reconstruction of the optical potential well was demonstrated.

A magneto-optic trap for micro-objects is described. Magnetic beads were trapped by optical tweezers while being rotated by a new integrated magnetic manipulator. Rotation was achieved with eight electromagnets with tip-pole geometry. The time orbital potential technique was used to achieve rotation of magnetic beads. Trapping in three dimensions and rotation of magnetic beads on three axes are demonstrated with forces up to 230 pN and force momenta of up to 10(-16)N m . A position-detection apparatus based on an interferometric scheme provides nanometer sensitivities in a few milliseconds.

We present an experimental setup to study terahertz dynamics in fluids under high pressure, employing inelastic x-ray scattering and diamond anvil cell techniques. The use of a carefully designed vacuum chamber and the minimization and control of sources of parasitic scattering allowed circumventing previous limitations due to important empty cell contributions to the scattering signal. The successful implementation of our setup is demonstrated in the case of supercritical fluid argon, for which a full viscoelastic analysis yields the dispersion relation of sound waves, the generalized heat capacity ratio, and longitudinal viscosity. Our results are in excellent agreement with available experimental observables and molecular dynamics simulations