We confine $^{85}\mathrm{Rb}$ atoms in an optical dipole force trap with a very large detuning from resonance of up to 65 nm. Confinement times 200 ms, limited only by background-gas collisions, are obtained without additional cooling. A typical contains 1300 at temperature 0.4 mK and peak density 8\ifmmode\times\else\texttimes\fi{}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. measure spontaneous photon scatter rates the trapped be less than...

We study the photoassociative collisional loss of laser-cooled Rb atoms from a far-off resonance optical dipole force atom trap. obtain well-resolved photoassociation spectrum 50 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ to 980 below first excited dissociation limit ${\mathrm{Rb}}_{2}$ molecule. Two vibrational series associated with $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathit{g}}^{+}$ states are clearly visible. Oscillations in Franck-Condon factors reflect structure triplet ground state...

We demonstrate hybrid femtosecond/picosecond (fs/ps) coherent anti-Stokes Raman scattering for high-speed thermometry in unsteady high-temperature flames, including successful comparisons with a time- and frequency-resolved theoretical model. After excitation of the N(2) vibrational manifold 100 fs broadband pump Stokes beams, coherence is probed using frequency-narrowed 2.5 ps probe beam that time delayed to suppress nonresonant background by 2 orders magnitude. Experimental spectra were...

The pulse-burst duration of a compact burst-mode Nd:YAG laser is extended by one order magnitude compared to previous flashlamp-pumped designs incorporating fiber oscillator and diode-pumped solid-state amplifiers. has linewidth <2 GHz at 1064.3 nm with 150 mJ per individual pulse 10 kHz. performance the system evaluated using third-harmonic output 354.8 for high-speed planar laser-induced fluorescence formaldehyde in lifted methane-air diffusion flame. A total 100 200 sequential images...

The hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent is used examine this recently developed probe technique, quantitative comparisons the full time–frequency evolution show excellent accuracy predicting experimental vibrational...

We study the states of ${\mathrm{Rb}}_{2}$ that lie within 35 ${\mathrm{cm}}^{\ensuremath{-}1}$ ${5}^{2}{S}_{\frac{1}{2}}+{5}^{2}{P}_{\frac{3}{2}}$ dissociation limit with photoassociation spectroscopy laser-cooled Rb atoms. observe rotationally resolved bound levels novel ${0}_{g}^{\ensuremath{-}}$ "pure long-range" state, which has an inner turning point beyond 25 bohrs. also identify belonging to ${1}_{g}$ and ${0}_{\ensuremath{\mu}}^{+}$ find are broadened by predissociation. With our...

We study the collisions of doubly spin-polarized ${}^{85}\mathrm{Rb}$ atoms at millikelvin temperatures using photoassociation spectroscopy. Because are spin polarized, only triplet collisional states formed. This leads to spectra a particularly simple form, which provide very direct probe ground state collision. These analyzed yield scattering length ${\ensuremath{-}1000a}_{0}<{a}_{T}<{\ensuremath{-}60a}_{0}$ for ${}^{85}\mathrm{Rb}$, ${+85a}_{0}<{a}_{T}<{+140a}_{0}$ ${}^{87}\mathrm{Rb}$,...

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging at repetition rates as high 1 MHz is demonstrated in the NASA Langley 31 in. Mach 10 hypersonic wind tunnel. Approximately 200 time-correlated image sequences of between and 20 individual frames were obtained over eight days tunnel testing spanning two entries March September 2009. The presented from boundary layer a 20° flat plate model, which transition was induced using variety different shaped protuberances, including...

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate single-shot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that affect nanosecond (ns) ps CARS, such as nonresonant background collisional dephasing, eliminated by selecting an...

Burst-mode planar laser-induced fluorescence (PLIF) imaging of the OH radical is demonstrated in laminar and turbulent hydrogen-air diffusion flames with pulse repetition rates up to 50 kHz. Nearly 1 mJ/pulse at 313.526 nm used probe P(2)(10) rotational transition (0,0) band A-X system. The UV radiation generated by a high-speed-tunable, injection-seeded optical parametric oscillator pumped frequency-doubled megahertz-rate burst-mode Nd:YAG laser. Preliminary kilohertz-rate wavelength...

The burst duration of an all-diode-pumped burst-mode laser is extended to 100 ms and kHz (10,000 pulses) by utilizing dual-wavelength diode pumping. Total energies 225 J at 10 400 are achieved during the period 1064 nm. This represents order-of-magnitude increase in number pulses compared with prior work, while maintaining similar or higher pulse energies. Amplitude tailoring each used flatten profile, reducing standard deviation energy over from 3.7% 2.1% a burst-to-burst 0.8%.

An all-diode-pumped, multistage Nd:YAG amplifier is investigated as a means of extending the duration high-power, burst-mode laser pulse sequences to an unprecedented 30 ms or more. The generates 120 mJ per at 1064.3 nm with repetition rate 10 kHz, which sufficient for wide range planar diagnostics based on fluorescence, Raman scattering, and Rayleigh among others. utility technique evaluated image formaldehyde fluorescence in lifted methane-air diffusion flame. advantages limitations diode...

Two-dimensional gas-phase coherent anti-Stokes Raman scattering (2D-CARS) thermometry is demonstrated at 1 kHz in a heated jet. A hybrid femtosecond/picosecond CARS configuration used two-beam phase-matching arrangement with 100-femtosecond pump/Stokes pulse and 107-picosecond probe pulse. The femtosecond generated using mode-locked oscillator regenerative amplifier that synchronized to separate picosecond burst-mode amplifier. signal spectrally dispersed custom imaging spectrometer detected...

The direct measurement of self-broadened linewidths using the time decay pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) signals is demonstrated in gas-phase N(2) and O(2) from 1-20 atm. Using fs pump Stokes pulses a spectrally narrowed ps probe pulse, collisional dephasing rates with constants as short 2.5 are captured high accuracy for individual rotational transitions. S-branch ~0.06 to 2.2 cm(-1) line separation triplet states obtained...

Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, low-temperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS employed minimize or eliminate influence of collisions for accurate, frequency-domain at elevated pressure. The ability ignore these interferences achieve thermometric errors <5% demonstrated N2 O2...

A high-speed, master-oscillator power-amplifier burst-mode laser with ∼100 ps pulse duration is demonstrated output energy up to 110 J per burst at 1064 nm and second-harmonic conversion efficiency 67% in a KD*P crystal. The distributed across 100 10,000 sequential pulses, 10 kHz 1 MHz repetition rate, respectively, over ms duration. performance of the evaluated been found compare favorably that similar design employs conventional ∼8 ns nearly transform-limited spectral bandwidth 0.15 cm(-1)...

A method for simultaneous ro-vibrational and pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is presented multi-species detection improved temperature sensitivity from room to flame conditions. N2/CH4 vibrational N2/O2/H2 rotational coherences are excited simultaneously using fs pump pulses at 660 798 nm, respectively, a common Stokes pulse nm. fourth narrowband nm ps probes all coherence states time delay that minimizes nonresonant background...

We study spin relaxation of optically trapped atoms that is due to light scattering from the trap laser. observe times greater than 2 s for ground-state hyperfine-level populations 85Rb in an optical dipole force operating as much 65 nm red D1 line. The measured rate can be more 100 slower atoms' total spontaneous scatter This enhancement atomic lifetime interference effect Raman far resonance.

Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) offers accurate thermometry at kHz rates for combustion diagnostics. In high-temperature flames, selection of probe-pulse characteristics is key to simultaneously optimizing signal-to-nonresonant-background ratio, signal strength, and spectral resolution. We demonstrate a simple method enhancing ratio by using narrowband Lorentzian filter generate time-asymmetric probe pulse with full-width-half-maximum (FWHM)...

A narrowband, time-asymmetric probe pulse is introduced into the hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering (fs/ps RCARS) technique to provide accurate and precise single-shot, high-repetition-rate gas-phase thermometric measurements. This narrowband pulse-generated by inserting a Fabry-Pérot étalon probe-pulse beam path-enables frequency-domain detection of pure-rotational transitions. The unique nature this pulse, in turn, allows for resonant...

Hybrid femtosecond/picosecond coherent anti‐Stokes Raman scattering (fs/ps CARS) of N 2 has recently been demonstrated for gas‐phase thermometry in reacting flows, enabling frequency‐domain detection at high repetition rates with excellent chemical specificity and independence from the effects collisions nonresonant background. In this work, we overcome limited sensitivity vibrational fs/ps CARS below 1200 K by spectrally resolving J ‐dependent rovibrational coherence revivals that occur 32...