The remote effect of the silyl group in stabilizing excited cation species was directly examined using transient absorption (TA) spectroscopy. The photoinduced cleavage mechanism of coumarins has been extensively studied, and the heterolytic dissociation of the C-X bond via a singlet excited state, leading to ion pair formation on an ultrafast timescale, is widely accepted (Figure ). Here, we focused on determining reaction yields and detecting processes following ion pair formation by monitoring delayed TA signals. The transient absorption (TA) spectra measured with a 25 ms delay revealed key features: a positive absorption below 330 nm, a negative peak at 385 nm, and a positive peak at 450 nm (Figure ). A previous study investigating the photolysis mechanism of coumarin derivatives reported similar TA spectral characteristics, indicating that the observed features correspond to the photolytic cleavage process of coumarin-based compounds. The negative peak at 385 nm represents the ground-state bleach of the coumarin chromophore, while the positive peaks at 330 and 450 nm are attributed to the formation of the photolytic compounds of coumarins. Despite differences in intensity, the spectra of Ester 1 and Carb 2 showed similar shapes, suggesting the formation of identical photoproducts. In contrast, Si-Carb 3 exhibited distinct features, including a shifted absorption peak. This observation is potentially associated with a unique photolytic reaction pathway of Si-Carb 3, resulting in the production of vinyl coumarin 6, as supported from the HPLC-MS and NMR analyses. To analyze reaction kinetics, TA signals were recorded at 385 nm for compounds 1-3 (Figure ). A fluorescence spike and a rapid absorption decrease were observed within the instrument's response time, with the latter indicating ion pair formation. This was followed by decays on the millisecond timescale, which subsequently plateaued. The TA signals were analyzed by a bi-exponential function (eqn (S1) in the Supporting information), with the resulting rate constants and amplitudes summarized in Figure . Notably, the rate constants showed minimal variation among the samples, indicating common underlying mechanisms despite the unique spectral behavior of Si-Carb 3. These processes are attributed to structural rearrangements and dissociation reactions. The absorption change at the plateau (Aplateau) followed the order Ester 1 > Si-Carb 3 > Carb 2, aligning with reaction yields determined by HPLC-MS. The higher yield of Si-Carb 3 compared to Carb 2 highlights the stabilizing excited cation species influenced by the β-silyl effect.