Average atomic weight: 9.0121831(5) u
| Isotope | Fraction | Atomic weight/u |
| 9 | 1(0) | 9.012183065(82) |
Atomic weights and isotopic compositions were obtained from NIST Database 144
Be I (Be-like): 197 levels, 3440 lines (E1: 2925 IC: 514 M2: 1), transition probabilities for 1752 lines
Be II (Li-like): 217 levels, 2844 lines (E1: 2844), transition probabilities for 789 lines
Be III (He-like): 194 levels, 1999 lines (E1: 1935 IC: 63 M1: 1), transition probabilities for 1838 lines
Be IV (H -like): 100 levels, 824 lines (E1: 824), transition probabilities for 824 lines
(Atomic Line List v3.00b5)
