The J-1000 Series Circular Dichroism spectrophotometers are specifically designed for high sensitivity measurements in the near- and far-UV regions, for scientists that need confidence in the data from characterization studies of biomolecule structure, function and stability under a wide variety of experimental conditions.
Unlike some detectors which only provide good signal-to-noise for low absorbing materials, the J-1000 Series circular dichroism spectrophotometers uses high dynamic range detectors to obtain high quality spectra of samples with excellent signal-to-noise, especially for highly absorbing materials found in the far- UV.

• High optical throughput
• Double prism monochromator providing low stray light
• Wide dynamic range PMT detector
• Highly efficient nitrogen purge system
• Digital signal processing
• Simultaneous Multi-Probe: CD, LD, HT, DC, absorbance, fluorescence

The innovative optical system of the J-1500 permits the measurement of a CD spectrum in the vacuum-UV region down to 163 nm. The enhanced light throughput and new digital lock-in technology now allows for a small signal in a very noisy environment to be detected. Additionally, the optimization of the nitrogen purge efficiency helps to reduce the amount of oxygen in the optical bench so that it does not bury the sample signal.
These features ensure that CD spectra can be obtained from strongly absorbing and high signal-to-noise (S/N) samples across the spectrum and into the vacuum-UV region. The quality of spectral data obtained, including data obtained at shorter wavelengths, substantially improves the accuracy of protein secondary structure analysis.

The PMT detectors used in the JASCO system are specially selected for the highest sensitivity and lowest birefringence. The wide dynamic range of the PMT detector ensures that large variations in signal intensity can still be detected, even for highly absorbing samples. The result is superior linearity between concentration and absorbance compared to other types of detectors including solid-state APD and CCD detectors.
The gain on a PMT detector is much larger (107) than most detectors, and therefore the signal amplification is larger. Under conditions with adequate light intensity, this typically leads to a larger amount of noise and therefore a lower S/N ratio. However, under conditions where there is a small amount of light hitting the detector (i.e. far-UV region), the gain of the PMT allows for good signal amplification at very low noise, increasing the S/N ratio.

The double polarizing prism monochromators of the J-1000 series result in stray light lower than 0.0003%, enabling the instruments to obtain high-quality CD data even under conditions with high absorbances.

The latest quad-channel lock-in amplifier provides simultaneous acquisition of up to four data channels including CD, HT, DC, absorbance, linear dichroism (LD), fluorescence, fluorescence-detected CD (FDCD), fluorescence-detected LD (FDLD) and fluorescence anisotropy.
Additionally, the lock-in amplifier obtains a signal at a specific resonance frequency while filtering out noise signals at other frequencies, helping to provide spectra with excellent signal-to-noise ratios.

Multi-probe measurement of Lysozyme showing the simultaneous acquisition of CD, Absorbance, Ex Fluorescence and Em Fluorescence during a thermal-ramping experiment.

High sensitivity combined with a 10,000 nm-per-minute maximum scan speed allows the J-1500 to measure samples quickly, increasing productivity in your lab. An additional benefit is the minimal time exposure of biological samples to the high-energy UV light, minimizing the risk of sample degradation. A mechanical shutter can also be programmed to open and close only during actual measurement to further avoid UV exposure.