Probe effects on time decays of coherent anti-Stokes Raman signals of isolated transitions

We show that time-resolved coherent anti-Stokes Raman signals of isolated transitions deviate from the exponential decay whose time constant is nowadays used for measuring Raman linewidths. The deviation is caused by probe pulse-shape effects that can be understood in terms of the spectral filtering created by the necessary action of laser probing. Consequent corrections to recent linewidth measurements on heteronuclear molecules support the unprecedented agreement between theoretical works and experiments.