FORM program sample lines

The ESR measurements were made at RT or 77 K on a Varian E-9 spectrometer (X-band), equipped with an on-line computer for data analysis. Spin-Hamiltonian parameters (g and A values) were obtained from calculated spectra using the program SIM14 A [26]. The absolute concentration of the paramagnetic species was determined from the integrated area of the spectra. Values of g were determined using as reference the sharp peak at g = 2.0008 of the E i center (marked with an asterisk in Fig. 3) the center was formed by UV irradiation of the silica dewar used as sample holder. 

For example, the calculated powder patterns for four of the polymorphs of sul-phapyridine are given in Fig. 4.22. The calculated pattern represents that of a pure sample. Using some of the more sophisticated programs to calculate the powder pattern, one can assume the absence of preferred orientation or alternatively some specified degree of preferred orientation. The line shape can be varied to match experimentally observed line shapes. If the crystal structures of all the polymorphic forms (and impurities) in the mixture are known, then the diffraction patterns... 

At the beginning, the qualitative study of these spectra was made by visual comparison using spectrographs. Nowadays these have been replaced by spectrometers capable of resolving line interferences and problems linked to matrix effects. Each element, whether in neutral or ionized form, is responsible for a range of lines of variable intensities. The instrument is therefore programmed to both identify and to quantify the elements in the sample to be measured. Instruments are classified into two major groups. 

To make the necessary measurements, vertical parallel lines are drawn on the tracing connecting the two marks at each subdivision the height of the schlieren curve at each subdivision is measured with a machine divider ruler (Paragon 56 3278, Keuffel Esser Co., Hoboken, New Jersey), and transcribed onto a prepared data form. The form also contains spaces for such data as identification number, run type, Spinco E machine used, frames read, dilution from the original sample, location of the major component, density and temperature of the run, constants that require redefinition for the analysis of the run, and a brief descriptive statement that can serve to further identify the run. Most of this information can be optionally left blank if it is not applicable, and the program will automatically substitute the standard values or options. 

---