Picosecond Vibrational Sum Frequency Generation (SFG) Spectrometer
Powerful and versatile tool for in-situ investigation of surfaces and interfaces:
Intrinsically surface specific
Selective to adsorbed species
Sensitive to submonolayer of molecules
Applicable to all interfaces accessible to light
Nondestructive
Capable of high spectral and spatial resolution
Features
High S/N ratio due to the superb laser source stability
Better than 6 cm-1 spectral resolution
Cost-effective picosecond system approach
Complete PC control
Acquisition of SFG spectra in wide wavelength range: 4300 每 625 cm-1
Monitoring of surface dynamics
Azimuth scan, XY-mapping of the sample (optional)
Models with 10, 20 or 50 Hz pulse repetition rate
Double resonance SFG model with tunable visible beam
Applications
Investigation of surfaces and interfaces of solids, liquids, polymers, biological membranes and other systems
Studies of surface structure, chemical composition and molecular orientation
Remote sensing in hostile environment
Investigation of surface reactions under real atmosphere, catalysis, surface dynamics
Studies of epitaxial growth, electrochemistry, material and environmental problems
Your application is welcome...
Picosecond sum-frequency generation (SFG) spectrometer from EKSPLA is an ideal tool in laser spectroscopy for in-situ investigation of surfaces and interfaces. The SFG spectrometer operates from 4300 to 625 cm-1 and provides < 6 cm-1 spectral resolution. The heart of the system is a picosecond Nd:YAG laser generating 25 ps pulses that pump an OPG/DFG delivering from 260 to 20 µJ per pulse across the IR range.
Basic operation principles of the SFG spectroscopy
In SFG experiment a pulsed tunable infrared IR (wVIR) laser beam is mixed with a visible VIS (wVIS) beam to produce an output at the sum frequency (wSFG = wVIR + wVIS).
SFG is second-order nonlinear process, which is allowed only in media without inversion symmetry. At surfaces or interfaces inversion symmetry is necessarily broken, that makes SFG highly surface specific.
As the IR wavelength is scanned, active vibrational modes of molecules at the interface give a resonant contribution to SFG signal. The resonant enhancement provides spectral information on surface characteristic vibrational transitions. Different combinations of input and output beam polarizations allow the determination of surface symmetry or molecular orientation.
SFG detects vibrational modes, which are rather localized to specific groups of atoms within the molecules. Information about relative orientation of different groups within the same molecule maybe obtained, and, hence, the molecular structure can be deducted.
Referring to the SFG signal phase measurements, information about the absolute orientation of molecule in respect to the surface can be obtained.
Software
All the spectrometer units (laser, optical parametric generator / amplifier / difference frequency generator (OPG/OPA/DFG), monochromators, photodetectors) are controlled from computer using LabVIEWTM environment. All the spectrometer units (laser, optical parametric generator / amplifier / difference frequency generator (OPG/OPA/DFG), monochromators, photodetectors) are controlled from computer using LabVIEW environment.All the spectrometer units (laser, optical parametric generator / amplifier / difference frequency generator (OPG/OPA/DFG), monochromators, photodetectors) are controlled from computer using LabVIEW environment. Spectrometer software features SFG spectra acquisition, azimuth scan, XY-mapping, surface dynamics investigation. OPG/OPA/DFG and monochromator calibration options are available.
1) Optional down to 16 µm (625 cm-1) upgrade is available
2) Optional upgrade with additional VIS@1064 nm is available
3) <10, for spectral range 210-419 nm
SFG spectrometer options
Spectral resolution down to 2 cm-1
Using narrowband OPO/OPA/DFG with synchronously pumped parametric oscillator decreases SFG spectral resolution down to 2 cm-1.
Second harmonic generation (SHG) spectrometer
Second harmonic generation (SHG) is an effective tool for surface probing. The monolayer adsorbtion may be detected by SHG. With different input/output beam polarizations SHG yield information on the average orientation of molecular adsorbates. The surface symmetry measurements can be performed by rotation of the sample around the surface normal. By using tunable lasers, SHG
establishes itself as powerfull tool for surface-specific electronic transitions spectroscopy.
SHG spectrometer is available as accessory to the SFG spectrometer or stand-alone system. Learn more about SHG...
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Design of the SFG spectrometer
SFG spectrometer includes:
Picosecond Nd:YAG laser
Optical parametric generator / amplifier / difference frequency generator (OPG/OPA/DFG)
Beams delivery optics
Monochromator
PMT or CCD signal detectors
Data acquisition system
Control software
Guiding beam for system alignment
Optional accessories:
Reference channel
Six axis sample holder (manual or three axes (X, Y and 牟 ) PC controlled)
Sample area purge box
Sum frequency excitation system is based on picosecond pump laser and optical parametric generator/amplifier/difference frequency generator (OPG/OPA/DFG).
Solid state mode-locked Nd:YAG laser featuring high pulse duration and energy stability is used to pump the system. Second harmonic (532 nm) of laser fundamental radiation is used as VIS pump beam for sum frequency generation.
Tunable IR radiation is generated in three stage optical parametric generator / amplifier / difference frequency generator. Spectral and spatial filtration of OPG seed beam provides narrow bandwidth and low divergency of mid-IR radiation. Beam walk-off compensation design ensures overlaping pump beams over the full wavelength range.
VIS beam delivery optics includes: spatial filter for homogenous beam profile, energy and polarization control system for smooth adjustment of pulse energy and polarization direction, delay line for temporal overlap of VIS and IR pulses.
IR beam delivery optics include mirror based polarization control and beam delivery systems.
The energy of both the VIS and IR beams is monitored by photodetectors for SFG signal
normalization.
Optional 6 axis (three translational and three rotational) including PC controlled X ,Y and 牟 stage enables sample mapping and investigation of molecules orientation.
SF guiding optics includes steering mirrors, focusing lens, polarization analyser and holographic notch filter for scattered VIS light rejection.
Detection system consists of monochromator and gated PMT based SF signal detector. ow power laser diode guiding beam is integrated for alignment convenience.
Optional reference channel improves the signal/noise ratio for samples with high non-resonant background.
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Double resonance model
Both IR and VIS wavelengths are tunable in double resonance SFG option. This two-dimensional spectroscopy is more selective than single resonant SFG and applicable even to media with strong fluorescence. Double resonant SFG allows investigation of vibrational mode coupling to electron states at a surface.
In double resonance SFG spectrometer model second OPG/OPA is used to generate tunable VIS beam in 210 每 680 nm range.
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Requests for custom made products are welcome.
Specifications are subject to changes without advance notice
Website:
http://www.oplanchina.com/
Telephone:
86-10-62623871
Address:
Rm.1006, Block 1st,Huihuang International Center. No.1st Shangdishi St.,Haidian Dist.,Beijing 100085, Beijing, China
