AbstractThe rotation‐vibrational Raman spectrum of thev11fundamental band of allene has been recorded. The spectrum consists of a series ofQ‐branches and partly resolvedJ‐structure in the subbands. TheQ‐branches in one component of the hot band 2v11–v11have been identified. the following constants have been obtained:v0= 352.73 ± 0.05 cm−1,A0= 4.811 ± 0.003 cm−1, ζ11= 0.816 ± ± 0.001, ΔA= −0.0129 ± 0.0003 cm−1, ΔB= (4.7 ± 0.6) × 10−4cm−1andDK= (2.4 ± 0.1) × 10−4cm−1. Anl‐type doubling is observed and thel‐type doubling constantq 11(−)is estimated as −(2.7 ± ± 0.8) × 10−4cm−1. The analysis of the Raman spectrum shows that the assignment of theQ‐branch maxima in the infr