Description
Increased sensitivity and decreased background noise are possible due to the ionizer design. An enclosed ion source operates with sample pressures as high as 10-3 torr with no need for futher pressure reduction of this differentially pumped inlet system. Higher sample pressures contain greater numbers of neutrals and more sample to ionize. With each order of magnitude increase in pressure, signal strength varies proportionally with sample density. This is accomplished by confining the sample within a (relatively) small ionization volume. The sample is constrained within the ion volume that that has a two small slits on either side of the ion volume. Bombarding electrons enter through these slits, ionizing the sample. Ions formed near the small exit hole of the ion volume are immediately extracted into the mass filter, and have little opportunity to react with neutrals. Ionization efficiency is high, since virtually the entire sample passes through the small ionization zone. The main transport mechanism from the source to the downstream mass filter is a pressure gradient, resulting from the higher pressure in the ionizer versus the lower pressure in the downstream mass filter. Hence, the source is conductance limited by the pressure difference.
Specifications –
| Mass Range | 1-100, 1-200, 1-300 AMU |
| Operating Pressure Range | 10-4 Torr to ultrahigh vacuum |
| Minimum Detectable Partial Pressure | 5 x 10-12 Torr ( 5 x 10-14 Torr for electron multiplier units ) |
| Resolution | Adjustable to constant peak width (0.5 AMU at 10% height) |
| Emission Current | 0.1 to 10 mA; 50 mA to degas |
| Electron Energy | 30 to 150 volts to operate; 200 volts to degas |
| Ion Energy | 1 to 10 volts |
| Source Sensitivity (Faraday Cup) | 2 x 10-4 Amps per Torr at detector (measured with nitrogen at mass 28) with peak width = 0.5 at 10% height and 1 x 10-3 Amps emission current |
| Power Requirements | 24 VDC @ 3 Amps; 110/220 VAC, 50/60 Hz adaptor available |
| Stability | |
| Mass Stability | ± 0.1 AMU after 30 minute warm-up |
| Peak Height | ± 2% after 30 minute warm-up |
| Minimum PC Requirements | Windows 98 through Windows 8 |
| RS-232 Serial Communications Interface |
Isolated; baud rate selection of 1200 to 38,400; 9-pin, female D-connectors |
| RS-485 Addressable Communications Interface | Isolated, baud rate selection of 1200 to 38,400; programmable addresses; 2-pin, female D-connectors |
| Optional Analog/Digital I/O Board | Includes two analog inputs, two analog outputs, six relay contact closures, and four digital inputs |
| Physical Dimensions | |
| Weight | 4.6 lb (2.1 kg) without head 74. lb (3.4 kg) with head |
| Width | 4.5 in. (11.4 cm) |
| Length | 9.0 in. (22.9 cm) |
| Height | 5.25 in. (13.3 cm) |
