Spectrometers

MOS-DAD.

Fast diode array spectrometer

A range of fast diode array systems including different wavelength ranges and resolutions designed to meet the needs of any kinetics research program

Diode array principle

A diode array instrument combines a two-dimensional pattern of diodes with a prism and is used to detect organic compounds. When the sample passes through the observation cell it is illuminated with white light. The light transmitted through the sample is dispersed by the prism so the different diodes can be considered as a single wavelength detector. The output from the array is used to construct the absorption spectrum. Absorption bands provide the user with information about the structure of the chromophore in solution.

 

Diode array for rapid kinetics

A diode array is often associated with a stopped-flow system when users needs to gain multi-wavelength information during rapid kinetics. Using one of our photodiode arrays, investigators can capture sub-millisecond resolution absorbance data, over a wide wavelength range, all in a single sample run. Bio-Logic offers a range of fast diode array systems (different wavelength range and resolution) to meet the needs of any kinetics research program. Spectra can be collected with a 400 µs time resolution from UV to near-IR, and the results can quickly identify reaction steps that can be studied in detail using conventional single wavelength systems. Thanks to its high speed and resolution, MOS-DAD is also perfectly suited to spectro-electrochemistry applications.

SVD analysis

Single value decomposition (SVD) is a recognized technique to analyze data generated by diode array spectrometers. The user can determine the number of chemical species involved in the absorbance changes and calculate their respective absorbance spectrum. Ultimately, once the reaction mechanism has been identified, the concentration profile over time of each species can be displayed. SFit and Biokine (proprietary software can address some reaction models, but all efforts have been made to ensure 3D data can be easily exported to external analysis software.

 

Bio-Logic diode array systems include software for system control and data analysis. Biokine provides full system control for the diode array, and for Bio-Logic stopped-flow mixers. Initial results are shown immediately, and the single control interface lets experimenters rapidly fine-tune the shot design and collection parameters to get results quickly.

Specifications

  • Detection mode: absorbance and transmittance
  • 256 to 1024 pixels
  • Acquisition rate: 400 µs/spectrum
  • Linear range from 0 to 2 AU
  • Wavelength range: 190-1100 nm (depends on the model selected)
  • Noise: better than 1x 10-4 AU (single scan)
  • Fiber optics connection to stopped-flow

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