1. The profile and width of the Spectral line
Spectral line wavelength also refers to its strength.
In fact every line is not truly monochromatic, but there is certain intensity distribution, so it has the line contour and width. Spectral line width is natural; Doppler becomes wider, collisions, and thus make the spectral lines have a certain profile and width. A wavelength refers to its strength at the maximum wavelength. Different spectral line with different width spectral lines, when do quantitative analysis ， the choice of spectral should be pay attention to.
2. Vapor cloud has a certain volume, the distribution of temperature and concentration in the volume is not uniform。
Radiation emitted by center, when through the edge, it was be absorbed, so that the temperature decrease.
This is because the atoms in high temperature steam centre was excited and launched the emission wavelength of spectral lines, and in the vapor cloud edge portion of the low temperature condition ，the atomic element can absorb the wavelength radiation.
The description of the Bio and Bie is indicated the absorption process.
When Do the photoelectric spectral analysis, attention should be paid to the analysis of line self suction degree, if the analysis line has a strong absorption, it will make the job slope of the curve reduced, and adverse for the analysis accuracy。The resonance line is the strongest self-absorption of each element, so only when there has the lower analysis element, it will adopt the resonance line as analysis line.If the Self suction are strongest, the spectral lines will formed a erosion (or self return), the original profile central intensity of the spectral line drops to zero, thus a line looks like two spectral line shape.Self etching line cannot be used as spectral quantitative analysis line.