Source Temperature

Ion source temperature plays an important role in ion generation. Specifically, desolvation is very important in the ionization process that occurs in an ESI source. 

---

A = effective surface area for heat and mass transfer in m L = latent heat of vaporization at in kj/kg k = mass-transfer coefficient in kg/ (sm kPa) t = mean source temperature for all components of heat transfer in K t = Hquid surface temperature in K p = Hquid vapor pressure at in kPa p = partial pressure of vapor in the gas environment in kPa. It is often useful to express this relationship in terms of dry basis moisture change. For vaporization from a layer of material ... 

According to KirehhofPs law, the emissivity and absorptivity of a surface in surroundings at its own temperature are the same for both monochromatic and total radiation. When the temperatures of the surface and its surroundings differ, the total emissivity and absorptivity of the surface often are found to be different, but, because absorptivity is substantially independent of irradiation density, the monochromatic emissivity and absorptivity of surfaces are for all practical purposes the same. The difference between total emissivity and absorptivity depends on the variation, with wavelength, of Zx and on the difference between the emitter temperature and the effective source temperature. 

The effect of radiation-source temperature on the low-temperature absorptivity of a number of additional materials is presented in Fig. 5-12. It will be noted that polished aluminum (cui ve 15) and anodized (surface-oxidized) aluminum (cui ve 13), representative of metals and nonmetals respectively, respond oppositely to a change in the temperature of the radiation source. The absorptance of surfaces for solar... 

Check and adjust source temperature prior to transfer... 

Therefore, the efficiency is raised by increasing the source temperature and decreasing the receiver temperature. 

Using either of the above approaches we have measured the thermal rate constants for some 40 hydrogen atom and proton transfer reactions. The results are tabulated in Table II where the thermal rate constants are compared with the rate constants obtained at 10.5 volt cm.-1 (3.7 e.v. exit energy) either by the usual method of pressure variation or for concurrent reactions by the ratio-plot technique outlined in previous publications (14, 17, 36). The ion source temperature during these measurements was about 310°K. Table II also includes the thermal rate constants measured by others (12, 13, 33, 39) using similar pulsing techniques. 

Factors may be classified as quantitative when they take particular values, e.g. concentration or temperature, or qualitative when their presence or absence is of interest. As mentioned previously, for an LC-MS experiment the factors could include the composition of the mobile phase employed, its pH and flow rate [3], the nature and concentration of any mobile-phase additive, e.g. buffer or ion-pair reagent, the make-up of the solution in which the sample is injected [4], the ionization technique, spray voltage for electrospray, nebulizer temperature for APCI, nebulizing gas pressure, mass spectrometer source temperature, cone voltage in the mass spectrometer source, and the nature and pressure of gas in the collision cell if MS-MS is employed. For quantification, the assessment of results is likely to be on the basis of the selectivity and sensitivity of the analysis, i.e. the chromatographic separation and the maximum production of molecular species or product ions if MS-MS is employed. 

Figure 16.2 Thickness determination of An deposition onto a bare silicon wafer using a 10 x 10 contact mask in two geometries (see insets), using (a) AFM along the diagonal of an array of 100 electrodes and (b) AFM and ellipsometry for a deposition geometry that allowed an average of 10 fields of identical thickness across the wedge. The source temperatures and deposition times were (a) 1548K, 7200 s and (b) 1623K and 4500 s.

Flow rate Injection volume Injection mode Injector temperature Ion source temperature Interface temperature Column temperature... 

Chlornitrofen and nitrofen conditions for GC/MS column, cross-linked methyl silicone capillary (12 m x 0.22-mm i.d., 0.33- am film thickness) column temperature, 60 °C (1 min), 18 °C min to 265 °C inlet, transfer line and ion source temperature, 260, 200 and 200 °C, respectively He gas column head pressure, 7.5 psi injection method, splitless mode solvent delay, 3 min electron ionization voltage, 70 eV scan rate, 0.62 s per scan cycle scanned mass range, m/z 100-400. The retention times for chlornitrofen and nitrofen were 11.8 and 11.3 min, respectively. The main ions of the mass spectrum of chlornitrofen were at m/z 317, 319 and 236. Nitrofen presented a fragmentation pattern with the main ions at m/z 283, 202 and 285. ... 

Mass-selective detector, MSD5973, electron ionization energy 70 eV, ion source temperature 135 °C mjz 412 (pyraflufen-ethyl), 398 (E-15), 326 (E-16) and 340 (E-3)... 

The appearance and reproducibility of chemical ionization mass spectra depends on the ionizing conditions, principally the source temperature and presstire and the purity of the reagent gas. Chemical ionization mass spectra are generally not as reproducible as electron impact spectra. 

Table 8.36 lists the main classical and newer approaches to solid sampling for elemental analysis. Little work on the introduction of solids into flames has been reported, because of problems of sample delivery and the relatively low source temperature. In arc and spark emission and in laser ablation as a sampling technique, the ablated sample material cannot be determined exactly. The limitations of arc or... 

The development and application of the method can be illustrated by considering the problem of integrating the utilisation of energy between 4 process streams. Two hot streams which require cooling, and two cold streams that have to be heated. The process data for the streams is set out in Table 3.3. Each stream starts from a source temperature Ts, and is to be heated or cooled to a target temperature Tt. The heat capacity of each stream is shown as CP. For streams where the specific heat capacity can be taken as constant, and there is no phase change, CP will be given by ... 

So transferring 30 kW will raise the temperature from the source temperature to ... 

Check the heat required to bring the cold streams from their source temperatures to the pinch temperature ... 

Note that stream 1 can not be brought to its target temperature of 40°C by full interchange with stream 3 as the source temperature of stream 3 is 30° C, so A7jllin would be violated. So transfer 1800 kW to one leg of the split stream 3. 

From Ref. 171. The mass spectra were recorded with a Jeol JMS-02-B mass spectrometer using an ionization potential of 75 eV. Unfortunately, the exact recording conditions, especially the ion source temperature, were not given (171). 

Representative mass spectral conditions (negative chemical ionization) ion source temperature, 150°C ionizing current, 0.20 mamp electron energy, 70 eV methane reagent gas (source pressure 0.5 to 1 torr). 

Pyrolysis spectra become distorted with respect to their diagnostic features for two major sets of reasons. The first is variations in instrument operation (e.g., heat transfer efficiency from wire to sample, ion source temperature, MAB gas identity, analyzer calibration, tuning, and ion transmission discrimination attributable to contaminated optics). Most of these factors can be controlled... 

With the surface ionization source it is generally assumed that the reactant ion internal state distribution is characterized by the source temperature and that the majority of the reactant ions are in their ground electronic state. This contrasts with the uncertainty in reactant state distributions when transition metal ions are generated by electron impact fragmentation of volatile organometallic precursors (10) or by laser evaporation and ionization of solid metal targets (11). Many examples... 

---