Vitro Technology, Ltd.

Hollow Cathode Lamps

Hollow Cathode lamps are line sources designed for use primarily in atomic absorption spectrophotometers,  Vitro offers the full range of single element, and a wide range of multi-element lamps. All variants are available in standard, data coded and Smith Heiftje background correction versions. Each lamp is optimized with regard to geometry, filler gas, gas pressure and window type to assure high intensity, low noise and long lamp life. Lamps are available with a 2 inch diameter for direct fitting into Perkin Elmer® instruments  and with a 1.5 inch diameter for fitting into all other commercially available instruments. Final testing of every lamp in the appropriate analytical instrument ensures the continuing optimal quality demanded by our clients throughout the world.

Our Hollow Cathode Lamps selection includes 70 single element and the widest range of proven multi-element combinations in standard 1 ½” (37mm) and 2” (50mm) diameters designed to fit directly into Perkin-ElmerÒ AA equipment.  Where appropriate these lamps are available with data coded bases permitting the instrument to automatically identify the lamp element. In addition a range of lamps specifically designed for use with Smith-HeiftjeÒ background correction system is available.

 Applications

Hollow Cathode Lamps are gas discharge devices in which the discharge is highly constrained around the cathode of a specific metal.  The resultant output is a unique line spectrum, the most intense of which are suitable for highly specific and sensitive metals analysis.  Further derivatives of the fundamental technology extend the applications to include: 

• Atomic Absorption Spectrophotometry

• Atomic Fluorescence Spectroscopy

• Multi-wave Laser Tuning

• Laser Output Stabilization

• Environmental Analyzers

• Medical Analyzers

Processing and Testing

Once the lamp is sealed the lamp is attached to the vacuum processing equipment via a pump stem and is subjected to a 16-hour program of evacuation, baking and cathode processing to a final fill with gas.  The processed lamp is then aged overnight on power supplies specific to the lamps final application to assure a stable and consistent product.  Finally the lamp is then tested for output, noise, drift and chemical sensitivity in an appropriate fully operational atomic absorption spectrophotometer.

Lamp Selection

Standard 37mm Lamps

Cathodeon 37mm hollow cathode lamps are suitable for most commercial atomic absorption instruments. It should be noted that when using 37mm lamps in instruments manufactured by GBC® and some Shimadzu® models require quartz windows.

Standard 50mm Lamps

These lamps are for direct use in Perkin-Elmer® Instruments utilizing the long established features of our standard range but making the necessary processing changes to ensure they are entirely compatible to these instruments.

Data Coded Hollow Cathode Lamps

Data Coded Hollow Cathode Lamps for Varian®, Perkin-Elmer®, and Unicam® instruments.  Data coded hollow cathode lamps incorporate a unique electronic configuration in the base or plug which the instrument recognizes and sets default operating conditions for the routine analysis of an element. 

Lamps for Self-Reversal (Smith-Heiftje®)

Background Correction Technique

Background correction in atomic absorption spectroscopy can use a Deuterium continuum method or the Zeeman method utilizing magnetic field polarization.  However both of these methods have limitations regarding the correction of uniformly distributed background.  An alternative method of Background Correction is the Self-Reversal (Smith-HeiftjeÒ) technique in which a high current is momentarily passed through the cathode producing a dense cloud of neutral atoms in front of the cathode which effectively cuts off the stream of photons produced during normal lamp operation at low current.  This momentarily stops absorption in the flame the spectrophotometer now reading the background absorption only, while at normal low current operation the instrument observes the sum of the absorption of the element and background. The spectrophotometer can then electronically subtract the background from the sample signal to solve the analytical problems that may be encountered with other methods of background correction.  Cathodeon has developed a range of lamps specifically designed to be uses at the currents recommended by the manufacturers of instruments where the self-reversal or “Smith-HeiftjeÒ” method of background correction is available.  These lamps have enhanced insulation to cope with the high voltage pulse used by this background correction method.

Multi-Element Lamps

Cathodeon manufactures the largest range of Multi-Element Lamps offering only those combinations, which provide sufficient energy and an acceptable lifetime for each element, with no spectral interference.  Multi-Element hollow cathode lamps are particularly useful when carrying out routine analysis on a number of different elements in the same sample where there is sufficient concentration of each element to allow easy detection. Multi-Element lamps are inevitably a compromise in which energy levels will be lower than single element lamps and hence noise levels may be higher.  This may limit ultimate detection levels, single element lamps being preferred wherever sensitivity is an issue. 

See Through Hollow Cathode Lamps

Cathodeon also manufactures opto-galvanic (see through) hollow cathode lamp, designed to act as a frequency stable reference for high intensity tunable monochromatic light sources, particularly lasers.

Vitro Technology, Ltd. 480 Barnum Avenue Bridgeport, CT  06608 Tel: (203) 366-0660 Fax:  (203) 366-8820 Email: sales@vitrotech.com