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(7.5-15.0) x 1014

(2.5-5) x 104

(3.0-6.0) x 102

Vacuum ultraviolet

~ 200-50

(1.5-6.0) x 1015

(5-20) x 104

~ (6.0-24) x 102

X-Ray

~ 50-0.1

~ (0.6-300) x 10"'

(0.2-100) x 10''

~ 103-106

y-Ray

< 0.1

~ 3 x 10'*

> 10«

> 10f'

" For kcal einstein divide by 4.184 (1 cal = 4.184 J).

" For kcal einstein divide by 4.184 (1 cal = 4.184 J).

TABLE 3.3 Some Relationships between Commonly Used Energy Units

X 1.196 X 10~2 = kJ moP1 X 2.859 X 10~3 = kcal moP 1 X 1.240 X 10~4 = eV

X 96.49 = kJ moP1 X 23.06 = kcal moP1 x 8.064 x 103 = cirT1

passes through a sample of length / (cm) and concentration C (mol L_l). If this wavelength is absorbed by the sample, the power of the beam exiting the sample is reduced to P (or I). The transmittance (T) is defined as ///„ (or I'//>,, ).

As the light passes through a thickness of sample dl, it undergoes a fractional reduction in intensity proportional to the absorbing path length, i.e.,

where the negative sign reflects the reduction in intensity with an increase in path length. Since the constant of proportionality must involve the concentration (C)

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