Magnets and cryostats
Placing the sample in a magnetic field allows measurement of magnetic circular dichroism (MCD) data. This method is a sensitive monitor of structural features that perturb the electronic states of an MCD active chromophore. In protein molecules, MCD offers a probe of a chromophore’s local environment because of its sensitivity to chromophoric electronic energy modulations induced by environmental perturbations. This technique has been generally used to study chromophores with large magnetic moments arising from rotational symmetries (aromatics, porphyrins), unpaired spins (metal complexes) or both (hemes). The MCD signal intensity is proportional to the magnetic field strength, which can be applied using either permanent magnets, electromagnets or super-conducting magnets:
JASCO offers a range of MCD options depending on the field strength and temperature desired, including:
• Permanent magnets with field up to 1.6 tesla at ambient temperature
• Electromagnets with field up to 1.5 tesla and low temperature cryostats
• Superconducting magnets with field of 8 tesla (and more)
MCD-581 Electromagnet
Measure magnetic hysteresis and MCD spectra in a continuously variable field from -1.5 to 1.5 tesla. This magnet has a pole gap of 15 mm and a pole diameter of 21 mm. A regulated DC power supply unit is used to control the magnetic field strength. The magnet requires cooling water (minimum of 5 L/min.) usually provided by a circulator system. Sample temperature can be maintained with an optional water-jacketed cell holder, which accommodates 10 mm cells. Spacers for 1, 2 and 5 mm cells are included. Optionally low-temperature cryostats (CRYS-582 and CRYL-583) are also available.
PMCD-593 Permanent Magnet
Measure MCD spectra in a fixed magnetic field of + or -1.2 tesla, according to the orientation. With a weight of only 5.9 kg, this accessory can easily be placed in and out of the standard sample compartment. The magnetic field is easily reversed by turning the magnet 180°. This magnet accommodates 10 mm path length rectangular cell holder as standard. Optional holders are available for cells with 1 mm, 2 mm and 5 mm path lengths.
PMCD-586 Permanent Magnet
Measure MCD spectra in a fixed magnetic field of + or -1.6 tesla, according to the orientation. With a weight of only 5.9 kg, this accessory can easily be placed in and out of the standard sample compartment. The magnetic field is easily reversed by turning the magnet 180°. This magnet accommodates 5 mm path length rectangular cells as standard. Optional holders are available for cells with 1 mm or 2 mm path lengths.
CRYS-582 Liquid Nitrogen Cryostat for Solid Samples
For solid samples, this cryostat has a temperature range from ambient down to -180 °C. Minimum sample size: 10 × 10 × 0.5 (t) mm, maximum sample size: 15 × 15 × 2 (t) mm
CRYL-583 Liquid Nitrogen Cryostat for Liquid Samples
For liquid samples, this cryostat has a temperature range from ambient down to -150 °C. Rectangular cells with 5 mm path length can be used.
Note: For both cryostats, temperature control is achieved with the TC-22HK3 Temperature Controller and a vacuum pump is necessary for adequate insulation of the sample holder unit and the liquid nitrogen vessel (2 L capacity).