72 
THE QUANTUM 
[V. 2 
ft 
Moseley found two lines in the K series, and several lines of the 
L series. He formulated the quantitative law that the frequency 
of any particular line in the X-ray spectrum is approximately 
proportional to A(Z — b) 2 , where A and b are constants. 
According to the law as enunciated by Moseley the square 
root of the frequency of an X-ray line (of a certain definite type) 
OLDER 8-27ÆBOI.3 
Ml 
ri 
^ 2 S 
rr 
1 1 
i i 
i i i i 
PaT 1 I 
rn 
I 
! 
MM MM: 
M Li ill 
MT 
11 ; i | ^ 
1 
t 11 
A 0, 1 1 1 
n 
I 
m! 
t'T 1 * 1 1 1 
1 1 1 1 1 1 1 
n 
1 1 1 
1 1 1 1 1 
“T' p 3 P- 
1 1 1 1 I 
! 
n 
1 
!. ! n !1 LI I 
K 
H'l | i j 
ItfEWER SYMBOLS 
(W) 
- (6.2.0 
O t (5,3,3) 
Oj* (=.3,2) 
O m (5,2,2) 
O, (5.2.0 
O, (5.1.0 
N,n (+,+.+) 
N w (+/fc3) 
N v (+.3,3) 
(+.3.2) 
N n (+2^) 
N, (+.2,0 
N (4,1,0 
^ (3,3,a) 
«nr (3.3,2) 
(3.2,2) 
M, (3,2,1) 
M, (3.1.0 
c* (wO 
(2,2,1) 
L. (2.1,0 
k (1.1.0 
Fig. ii.—Atomic Energy Levels (Bohr and Coster). 
is a linear function of the atomic number. This can only be 
regarded as a first approximation, for when these quantities are 
plotted the graph obtained is slightly curved. According to the 
quantum theory the frequency of a spectral line cannot rigorously 
obey a law of this kind, for it is determined by the difference 
between two terms. The law may, however, be applied to the 
frequencies of the absorption discontinuities described below. The