Alpha-particle cluster states in ¹⁸F and ¹⁸O

Several levels in ¹⁸F and ¹⁸O are assigned to rotational bands based on ¹⁴N + α and ¹⁴C + α cluster configurations. In ¹⁸F, we predict the existence of K^π = 0⁺ and 1⁺ bands, consisting of states with spin and parity 1⁺, 3⁺, 5⁺, 7⁺ and 1⁺, 2⁺, 3⁺,..., 9⁺, respectively. Experimental candidates for several of these states are proposed, and we show that by considering the tensor component of the ¹⁴N + α interaction the experimental level scheme is quite well explained. We calculate E2 and M1 transition rates within these bands of states and obtain good agreement with experiment. We also suggest candidates for the 0⁺, 4⁺ and 6⁺ members of the ¹⁴C + α cluster bands in ¹⁸O. Finally, we discuss the similarities between the α-cluster bands in ¹⁸O, ¹⁸F, ¹⁹V and ²⁰Ne and show that stable α-particle structures do appear to persist from nucleus to nucleus.