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GENERAL: See also (1985AJ01) and Table 11.1 [Table of Energy Levels] (in PDF or PS).

The mass excess is 40.94 ± 0.08 MeV (1875TH08), 40.78 ± 0.12 MeV (1988WO09). A.H. Wapstra suggests (private communication) 40.85 ± 0.08 MeV and we adopt this value. ¹¹Li is then bound with respect to ⁹Li + 2n by 247 ± 80 keV and with respect to ¹⁰Li + n by 1050 ± 260 keV [see the masses of ⁹Li and ¹⁰Li in (1988AJ01)].

The magnetic moment of ¹¹Li is μ = 3.6673 ± 0.0025 nm (1987AR22). This value requires J = 3/2 (1987AR22). Negative parity is certain from systematics.

The interaction nuclear radius of ¹¹Li is 3.16 ± 0.11 fm (1988TA10, 1985TA18), E = 790 MeV/A; [see also for derived nuclear matter, charge and neutron matter r.m.s. radii]. ¹¹Li has a much larger radius than other neighboring nuclei suggesting either a large deformation and/or a long tail in the matter distribution in ¹¹Li (1985TA18). See (1988SA2P) and (1987MI38, 1987TAZU, 1989TA1K). Charge radius and matter radius calculations in the 0ℏω and (0+2)ℏω model spaces predict a gradual increase in matter radii with increasing A and do not support the idea of a neutron halo in ¹¹Li (1988POZS; prelim.). See, however, (1988TA1A).

Fragmentation cross sections of ¹¹Li into ⁹Li, ⁸Li, ⁸He, ⁷Li, ⁶Li and ⁶He have been studied by (1988KO10) [see for a discussion of neutron halos]. See also (1988TA1A, 1989KO1P).

See also (1986DU11, 1988ST06), (1986AN07, 1988HA1Q, 1988TA1C, 1989AJ1A) and (1985SA32, 1986EL1A, 1986SA30, 1987HA30, 1987SH1K, 1988BE09, 1988BE1O, 1988JO1C, 1988LO1C, 1988UC03, 1989BA1T, 1989BE03; theor.).

1. 11Li(β-)11Be

Qm = 20.68

Reported half-life measurements are 8.5 ± 0.2 ms (1974RO31), 8.83 ± 0.12 ms (1981BJ01), 7.7 ± 0.6 ms (1986CU01). We adopt 8.5 ± 0.2 ms. The β-decay is complex and the evidence is not unambiguous. It involves delayed n, t and α emission. Most of the decay (approximately 97%) takes place to low-lying states in ¹¹Be [but it is not clear which are involved]. All but ¹¹Be*(0, 0.32) are unstable with respect to neutron emission: see (1985AJ01). A 2.9% branch is reported to ¹¹Be*(10.59) which then decays by neutron emission (possibly to ¹⁰Be*(9.4)) and then delayed α-particles [(0.90 ± 0.05)%] are reported to ⁶He or the decay is via 2n + 2α[(2.0 ± 0.6)%] (1981LA11). A (0.30 ± 0.05)% branch is reported to a state in ¹¹Be at approximately18.5 MeV (Γ0.5 MeV) which has three modes of decay: triton emission to ⁸Li*(0, 0.98) [(0.010 ± 0.004)%], (α + n)-emission to ⁶He[(0.10 ± 0.03)%] and 3n emission [(0.20 ± 0.05%] involving ¹⁰Be*(11.76) (1981LA11, 1984LA27). [Comment: In view of the importance of understanding very neutron rich light nuclei it is necessary to determine the parameters (and the location) of the excited states of ¹¹Be with E_x is approximately equal to 12 MeV. One could then hope to unravel the β^- decay evidence.] See also ⁶He, ⁸Li and ¹⁰Be in (1988AJ01), Table 11.2 (in PDF or PS) in (1985AJ01), (1985HA1T, 1985HA1K) and (1984LI1N, 1988JO1C; theor.).