Assertion: population inversion | /r/HasProperty | achieved at the frequency
Facets:
value: between level
type: LOCATION
value: between 2
type: TEMPORAL
value: between optical amplification
type: OTHER
Source sentences:
text: A population inversion (N 2 > N 1 ) has thus been achieved between level 1 and 2, and optical amplification at the frequency ν 21 can be obtained.