Q. What is the difference between standard lamps and coded lamps?

A. The only difference is that a coded lamp allows the newer Atomic Absorption Spectrometer instruments to recognise the lamp. ie the instrument automatically knows the lamp is a Copper lamp with a wavelength set to 324.8nm etc, while a standard lamp will not be recognised. This is not totally necessary and is mainly used for automation i.e. overnight runs.

Q. What is the difference between the Standard 37mm HC lamps and the Standard 51mm Perkin Elmer lamps? Just the length and the glass window, or also a difference in brightness?

A. The main difference is the diameter of the lamp envelope. This means more gas is contained in the standard PE type, hence a longer lamp life. However the P903 (arsenic) is an exception because it has some intensity problems and we recommend using the smaller 37mm type or a super lamp. Quartz or pyrex windows depend on wavelength recommended for each element. Each different element lamp varies in intensity e.g an arsenic lamp is not as intense as a copper lamp. Historically the two types come from two different companies Varian = std 37mm lamp and Perkin Elmer = 51mm Lamp.

Q. Why are SUPER Lamps super?

A. Well, for say 15 elements, the intensity is up to 15 times greater than a standard hollow cathode lamp. Arsenic and selenium Super lamps are the most popular. The reason for the greater intesity is that of a secondary discharge. Sulivan and Walsh of CSIRO developed this idea and called it a Boosted discharge lamp. This concept was further improved by R.M. Lowe of the same group. Photron used his concept and improved the design and cathode material which resulted in the Super Lamp.

Q. Which sort of fill gas do the Standard Hollow Cathode Lamps use? Neon? (if yes, are other fill gasses available as well, e.g. Argon ??)

A. Filling Gas is mostly neon and  argon can also be used, all other noble gases are available. Deuteruim gas is available for a few elements (D2 is a reactive gas).

Q. Do you have lamp mounts/holders and power supply for these lamps too?

A. We do make a Power Supply for HCL lamps, However as this is not sold very often we need 4 weeks lead time. Power supplies will be built with your purposes in mind. As for lamp mounts or holders we can have them custom built, we will quote you.

Q. Can we use Photron lamps as substitutes for IL Visimax lamps?

A. Yes, these are the same lamps.

Q. Do Super Lamps For a PE 3110 need a special power supply?

A. Yes, they require the Photron Power Supply (Part Number P8200A). At present, all PE instruments require our power supply; only some GBC instruments have our Power Supply in built. The new Unicam instrument also has a power supply able to run Super lamps.

Q. Can you supply HCL lamps for a PE3300?

A. Yes, please refer to Photron's P900 series of hollow cathode lamps.

Q. Why is the light output modulated?

A. Modulation is more to do with the instrumentation, i.e. Atomic Absorption Spectrometers, than our lamps. However, using modulation on our lamps will generally increase lamp life, because the lamp is only at the recommended current at the peak of the cycle. If modualation is not used then a flat DC signal applies.

Q. There were inaccuracies in the installation instructions for the last Super Lamp power supply we received. The Instrument is Varian Spectra 300/400 8-place lamp turret. Instruction says connect yellow wire but there is none although there is a red wire. Please explain how to install the power supply.

1. Disassemble one turret on wheel suggest turret No 4 or No 1.
2. Desolder and isolate connecting wires to pin5 and 7 on octal socket. This is for coded lamp signal and must be disconnected for super lamp    position.
3. Drill hole through the release button (lamp clamp).
4. Desolder pin 1 and 3.
5. Insert lead of adaptor kit through wheel and lamp clamp.
6. Insert spring over lead.
7. Cut wire end to suitable length and fit appropriate heat shrink over red and black wires.
8. Solder red wire to wire that was connected to pin 3 and black wire to wire from pin 1 and insulate with the heat shrink.
9. Solder Blue wire to pin 1.
    Solder Violet wire to pin 7.
    Solder White wire to pin 3.
    Solder Orange wire to pin 5.
10. Reassemble turret assy to wheel
11. Connect octal plug P1 to octal socket on flying lead from Super Lamp Power Supply.
12. Connect octal socket S1 to male octal plug mounted on rear of Power Supply.

Q. How exactly do hollow cathode lamps operate in AA Spectroscopy Instruments?

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             A. Hollow cathode lamps produce a spectral line source of the element or elements contained within the lamps cathode. A common type of AA spectroscopy (Double beam AA) splits the hollow cathode lamps beam into two, one as a reference beam, the other to pass through a flame or furnace of free atoms. The beam passing through the flame or furnace is then partially absorbed by the free atoms of the same element that is within the cathode of the lamp. Hence, the difference between the two beams is proportional to the concentration of the element within the sample solution.

Q. How can a dual lamp like a Ca/Mg lamp  detect both metals in a sample? What wavelength is recommended?

A. The hollow cathode lamp cathode material is made up of Calcium and Magnesium alloy. When running this lamp in an Atomic Absorption spectometer you must tune the instrument to the appropriate wavelength of each element you wish to analysis. So for a Ca/Mg lamp, tune your instrument first to 422.7nm for Calcium and then to 285.2nm for Magnesium or vica versa.

Q. Will  the spectral line width be increased by changing the pressure in a hollow cathode lamp?

A. Changing the pressure in a hollow cathode lamp will do very little to the spectral line, e.g it may change by 0.3 of an angstrom. If the pressure is increased too greatly the lamp will no longer operate as a glow discharge.

Q. How does a hollow cathode lamp work?

A. A hollow cathode lamp is a "glow discharge lamp". It works by having a potential difference between two points (anode +ve and a cathode -ve) and an inert gas between them at a particular pressure. The inner lining of the cathode is made from the desired element and this element is struck by ions. The ions cause atoms of the element to be removed from the surface. This is called sputtering.

Q. What is the black/silver spot in Photron hollow cathode lamps?

A. The black/silver spot is what we call the getter. If you look closely at the centre of the black spot on the internal lamp structure you will see a ring. This ring is a barium getter. It has been activated by an RF generator; hence the black/silver spot. What does it do? The material on the inside wall acts as a trap, to catch impurites within the gas of the lamp. If a di-atomic particle hits this material, it becomes stuck to the wall. Therefore the getter keeps the gas clean throughout the life of the lamp.