Transient absorption spectroscopy

Transient absorption spectroscopySpecially designed for measuring transitions between quantum states in optically excited samples. TA measurement is applicable to both liquid and solid sample types.
The ground state sample is excited to an excited state by a strong laser pulse. Pulses may induce short-lived intermediates, such as higher energy level electrons, free radicals, or ions. In the case of liquids and films, the de excitation process is monitored by measuring the transmittance/absorbance of the white light beam passing through the sample, or by measuring the reflectivity of the sample in the case of powder and opaque bulk samples. The white light beam is generated by a xenon lamp. The system provides the ability to measure fluorescence and phosphorescence induced by laser pulses. Through electrochemical extension, solid-state samples immersed in electrolytes can be studied. When inspecting samples in contact with electrolytes, additional bias potentials may be applied during the experimental process. This provides an additional control parameter and expands the flexibility of the experiment.

Transient absorption spectroscopyMeasured parameters:

The transmittance/absorbance or reflectance of the sample (expressed in nanoseconds time scale),Laser-induced fluorescence spectroscopy/

The lifetime of photoexcited transients,The laser beam intensity on the input and output of the sample chamber,I-V characteristics of electrochemical samples (charged chemical extension).

Current between sample and electrolyte during laser pulse (using analog potentiostat)

The system includes the following configurations:

Closed sample room.

Xenon lamp with water cooling system and pulse generator.

Laser, usually Nd: YAG, can choose high-order harmonics or even OPO.

Grating for UV, VIS, and IR spectral ranges.

oscilloscope

photomultiplier tube

Synchronize the timers of all components in the system.

The electrochemical workstation provides all the characteristics of electrochemical samples.

Electrochemical colorimetric dish with platinum electrode and Ag/AgCl reference.

sample room

The sample room will be shielded from background diffuse light and external electromagnetic fields for measurement settings. It is equipped with a safety system that disconnects the power supply to the xenon lamp and laser source after opening the chamber, as well as a simple and stable system for installing various experimental devices.

We can provide internal measurement devices with different optical paths and sample colorimetric dishes, and adjust them according to their respective experimental requirements.

Technical Specifications:

sample room

When the sample chamber is opened, disconnect the safety system of the xenon lamp and laser power supply,Easy and stable installation of various experimental devices using sample colorimetric dishes,Two photodiodes: located at the entrance and output of the chamber, used to measure laser pulse power,

xenon lamp

150 W xenon lamp,Water cooling system/Low electromagnetic emission igniter/Stable light intensity mode, providing a constant light power of the beam,Default beam diameter: 8 mm,Used in conjunction with a filter wheel to modify the detection spectrum,

Xenon lamp pulse generator

Pulse duration: 2 μ s ÷ 2 ms,

Pulse current: 8.5 ÷ 595 A.

laser source

Laser type: Nd: YAG with a baseline of 1064 nm,

Up to four harmonic generation modules: 213 nm, 266 nm, 355 nm, 532 nm

Beam diameter: 5 mm,

Pulse duration: 5 ns,

Beam power: 532 nm: 200 mJ, 350 nm: 100 mJ (10 Hz),

Any other laser type or OPO can be used at the entrance of the sample room.

Filter wheel

Up to 6 filters,

By default, two edge (long pass) filters are provided: 400 nm and 600 nm,

The optional air quality filter is installed in the filter wheel and coupled with the xenon lamp,

photomultiplier tube

Anode to cathode voltage range: 500 ÷ 1200 V,

Spectral range: 160 ÷ 900 nm,

potentiostat

Standard or simulation

Standard electrochemical workstation (used for setting bias potential and slow current measurement):

- Bandwidth: 500 Hz,

Sampling: 1 kHz,

- Current resolution: 1 pA to 100 nA (depending on the range),

Simulated electrochemical workstation (for fast photocurrent measurement and fixed bias potential):

- Bandwidth: 500 MHz,

- Bias current compensation,

- Measurement range: 10 mA/V; 1 mA/V; 100 μA/V; 10 μA/V; 1 μA/V; 100 μA/V，

Bias potential range: -5 V ÷ 5 V,

Dual electrode or triple electrode configuration,

timer

Time analysis: 50 us,

Trigger frequency: can be adjusted through software to match the laser pulse rate,

Control experiment timing and synchronization: laser pulse, oscilloscope, input and output shutter, potentiostat

Through software,

Two input channels for measuring laser pulse power,

oscilloscope

Bandwidth: 300 MHz,

Sampling rate: 5GSample/s,

experimental setup

Standard Configuration

Instantaneous absorption

Quasi Co linear transient absorption

Laser-induced fluorescence

electrochemistry

The diffuse reflectance of powder samples,

Difference Reflectance: Reflectance of Solid State Samples in Contact with Electrolytes