Molecular Iodine Cells

Iodine Cells

The spectrum of molecular Iodine includes discreet rotational and vibrational bands with very fine structure in the visible (490-650 nm) spectrum.  For this reason, Iodine has been used as frequency references for years.  More recently, Iodine has been used as frequency discriminators in Planar Doppler Velocimetry (PDV) and Filtered Rayleigh Scattering (FRS) systems.  

Transmission versus frequency for 5-inch iodine cell at a range of vapor pressure set points. Long term stability of sealed Iodine Cell

When used in PDV/FRS systems, the stability of the Iodine cell transmission-vs-frequency profile has been identified as a significant source of error.  This instability is caused by variations in the Iodine number density.  The number density (pressure) of the Iodine vapor is a strong function of temperature, and therefore, small changes in cell temperature (~ 0.1 °C) can have significant impact on the transmission-vs-frequency profile.  An improved design, the starved or super-heated vapor cell, is the basis of the ISSI cell design.

Sealed Iodine Cell Connected to Temperature Controller


Permanently Sealed Iodine Cells

(Product ID:I2S-5, I2S-10)

To create the permanently sealed starved cell, the cell is evacuated and cold-finger filled with Iodine is brought to the desired vapor pressure (cold-finger operating temperature). The stem between the cold-finger and cell is then permanently sealed with a torch, isolating the Iodine in the cell body and fixing the number density. The cell is then operated 10-20 °C above the cold-finger set temperature and the Iodine in the cell is a super-heated vapor with a set number density. The result is a molecular cell with a very stable absorption spectra.

5-Inch Sealed Cell 10-Inch Sealed Cell

Permanently sealed iodine-vapor cells are 3-in.-dia, 5-in.-long or 10-in.-long Pyrex cells. The cells feature an integrated Type T thermocouple and rugged aluminum housing. These cells are manufactured with a prescribed iodine partial pressure (specified by user at time of order). In addition, the transitions can be pressure broadened with nitrogen partial pressure (specified at time of order). 


Ordering Information

  • Specify length of 5-inch (I2S-5) or 10-inch (I2S-10)
  • Specify Set Point Temperature

Downloads

Permanently Sealed Iodine Cell Data Sheet.pdf


Manifold Iodine Cells

(Product ID: I2M-5, I2M-10)

To create a sealed starved cell with a flexible set point, a glass cell with an attached cold-finger and vacuum port is constructed. The vacuum port and cold-finger include stopcocks. The cell is evacuated and cold-finger filled with Iodine is brought to the desired vapor pressure (cold-finger operating temperature). The stem between the cold-finger and cell is then sealed by closing the stopcock, isolating the Iodine in the cell body and fixing the number density. The cell is then operated 10-20 °C above the cold-finger set temperature and the Iodine in the cell is a super-heated vapor with a set number density. The result is a molecular cell with a very stable absorption spectra.

Iodine-vapor cells with a manifold are 3-in.-dia, 5-in.-long or 10-in.-long Pyrex cells.  Standard cells are manufactured with 1/4 grams of iodine (actual pressure determined by temperature of water cooling jacket at the time of operation).  The cells feature an integrated Type T thermocouple and rugged aluminum housing.  These cells are manufactured with a prescribed iodine partial pressure (specified by user at time of order).  In addition, transitions can be pressure broadened with buffer gas supplied by user through a fill-port.

Cell Profile Showing Manifold

Ordering Information

  • Specify length of 5-inch (I2M-5) or 10-inch (I2M-10)
  • Specify Set Point Temperature


Downloads

Manifold Iodine Cell Data Sheet.pdf

Manifold Iodine Cell Operating Instructions.pdf


For ordering information please contact our sales department: issi-sales@innssi.com or call us at (937) 630-3012

For technical support, please contact our support department: support@innssi.com or call us at (937) 630-3012