Recording Incoming Orientations

To preserve styles and orientations, certain starting orientations are perceived and recorded (this is not relevant if one is drawing de novo). These include the following. 

CCW substituent order. That the circular order of substituents may be preserved, the CCW (or CW) order of substituents about every atom is noted. Additionally, to ensure that sulfone oxygens (for example) are placed in opposition, this is a convenient spot to modify the sulfur s substituent order. 

Bond directions. To preserve overall molecular orientation (see later section on Preservation of Molecular Macroorientation), the directions of individual bonds are recorded. 

The information gleaned from the preceding conventions is discussed further in the assembly and postassembly sections. 

It is assumed that ring information is available to the SDG program its perception is not discussed here. Three nonexclusive methods have been used to assign coordinates to ring systems (RSs)  

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During preassembly analysis, the direction of each bond is noted as explained earlier (see section on Recording Incoming Orientations). 

Figure 14.4a shows some NEXAFS spectra from samples prepared at constant growth rate (0.9 nm/min) but at three different sample temperatures of 101, 303, and 373 K. The spectra were recorded with s- and p-polarisation of the incoming light the respective experimental geometries are depicted in Figure 14.4d. The spectra are dominated by sharp pre-edge resonances at about 285 eV, which can be associated with transitions from C Is core states into the lowest unoccupied molecular 7t -orbitals. The average molecular orientation,...

The continuous-wave (cw) PL spectra of the M-plane GaN films (samples VII and V111) were excited at 244 nm by a frequency-doubled Ar+ laser, dispersed by a 1-m monochromator, and detected by a UV-enhanced GaAs photomultiplier. The polarization properties of the PL spectra were studied by polarizing the emitted PL signal before it entered the monochromator. All spectra were recorded under normal incidence so that the c axis of the GaN films was oriented perpendicular to the propagation direction of the incoming light. Excitation power densities of up to 50 W cm were used. 

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