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Department

of

 Chemistry

Lab

Our laboratories are located in the basement of the WSU Chemistry department  (room 70).  This helps with the vibration isolation and temperature stability necessary for our laser spectroscopy experiments.

The facilities occupy over 2,000 sq. ft. of space, and include student offices and wet labs with 90 sq. ft. of bench surface and  2 fume hoods.  

Our laser spectroscopy lab is a specially designed 600 sq. ft. clean room equipped with an ultrastable climate control system (±1 ^oF temperature and <50% humidity year-round). 

Our surface spectroscopy set-up is based on a high-power Ti-Sapphire femtosecond laser system (oscillator - KML, pump lasers and amplifier - Spectra-Physics) which outputs 2 mJ/pulse (1 kHz) at the 800 nm fundamental wavelength.  The pulse duration is 35-40 fs. 

The fundamental output is split into two beams (50-50). One of them is used to pump an OPA (Optical Parametric Amplifier,  Spectra-Physics), and then generate femtosecond mid-infrared pulses (65-85 fs, 3-5 μJ/pulse, 3300−1500 cm^-1) by difference frequency mixing.  The other portion is used to produce the visible beam for our IR+vis Sum Frequency Generation (SFG) experiments.  The signal generated at the sample surface is frequency-dispersed through a monochromator (Roper Scientific Spectra-Pro-300i) and detected using a high quantum efficiency liquid-nitrogn cooled CCD (Princeton Instruments Spec-10:100B).

As described in the "Research" section, our set-up combines several versions of the vibrational SFG spectroscopy:

(1) The Broad-Band SFG (BB-SFG), where a broad-band (femtosecond) IR pulse (typically, 200−300 cm^-1) is combined with a narrow-band (picosecond) visible pulse (typically, 5−15 cm^-1), and the SFG spectrum is recorded in the frequency domain.

(2) The time-domain SFG Free Induction Decay (SFG-FID) technique, where both IR and vis pulses are short (typically, 35−85 fs), i.e. broadband, and the SFG signal is recorded  as a function of the IR-vis time delay.

(3) The mixed frequency-time-domain STiR-SFG technique (Spectrally and Time-Resolved SFG), a version of SFG-FID where the signal is dispersed through the monochromator to measure its spectra evolution during the free induction decay.

(4) The new Heterodyne-Detected SFG (HD-SFG), which significantly improves the sensitivity and detection limits well below a single monolayer surface coverage (paper submitted for publication) and, at the same time, obtain phase information on the vibrational transitions. 

Polarizations of the IR, visible, and SFG beams are controlled in order to obtain information on orientation of molecules at the surface/interface. 

We use many other characterization techniques and instruments available in the Department's Central Instrumentation Facility (CIF), including UV-vis, FTIR spectrometers, TEM, SEM, mass spec, NMR, and XRD.

Laser spectroscopy set-up layout

Our laser system is enclosed to prevent air currents

Wet lab