Room-temperature laboratory spectrum of vinyl cyanide in the region of the 4₁₃ − 3₁₂ rotational transition recorded with a Stark modulation spectrometer. All marked lines are for the 4₁₃ − 3₁₂ transition in a given vibrational or isotopic species and display a characteristic pattern of negative lobes due to the non-zero field cycle of Stark modulation. Dotted lines connect vibrational states analyzed as perturbing polyads, red denotes vibrational states analyzed in the present work, and asterisks identify states detected presently in Orion-KL. It can be seen that laboratory analysis is now available for excited vibrational state transitions that are comparable in room-temperature intensity to those for ¹³C isotopologues in terrestrial natural abundance.