[en] Additive effect of 1-chloropentane (1-C₅H₁₁Cl) in γ-irradiated n-hexane (n-C₆H₁₄) at 77 K has been studied by the analysis of the decomposition products (hydrogen (H₂), hexenes (C₆H₁₂), and dodecanes (C₁₂H₂₆)). Addition of 1-C₅H₁₁Cl reduced the yields of the decomposition products. The dessociative electron capture of 1-C₅H₁₁Cl is considered to suppress the recombination of n-C₆H₁₄ cation and electron and reduce the yields of hexyl radical (C₆H₁₃ ·), hydrogen atom, C₆H₁₂, and H₂ as the recombination products. The decrease of the H₂ yield is also attributable to the reduced yield of hydrogen atom which produce H₂ with hydrogen abstraction from n-C₆H₁₄ molecule. The decrease of C₆H₁₃ · suppresses the production of C₆H₁₂ and C₁₂H₂₆ which is produced by the disproportionation and recombination reactions of C₆H₁₃ ·, respectively. The ratio of the disproportionation and recombination reaction rates of C₆H₁₃ · at 77 K was estimated to be 2 ∼ 2.3. (author)