Table 5. Calculated microscopic parameters for energy transfer process, the number of phonons necessary to assist the energy transfer and the percentage of each phonon participated in the process in Y2Er and N2Er samples.

Sample	Energy transfer	N (number of phonons) (% phonon assisted)		CD-A (×10−40 cm6 s)
Y2Er	ET1 (4I11/2→4I11/2)	0	1	2.68
		99.99	0.01
	ET2 (4I13/2→4I13/2)	0	1	10.4
		100	0
N2Er	ET1 (4I11/2→4I11/2)	0	1	4.17
		99.986	0.014
	ET2 (4I13/2→4I13/2)	0	1	13.0
		100	0