1a:I[76865,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"Grid"] 1b:I[17291,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"GridCol"] 1c:I[34616,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"Avatar"] 1d:I[32972,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"default"] 1e:T4bc,Internal conversion (IC) is a common radiationless transition in polyatomic molecules. Theory predicts that molecular vibrations assist IC between excited states, and ultrafast experiments can provide insight into their structure-function relationship. Here we elucidate the dynamics of the vibrational modes driving the IC process within the Q band of a functionalized porphyrin molecule. Through a combination of ultrafast multidimensional spectroscopies and theoretical modeling, we observe a 60 fs Q_y-Q_x IC and demonstrate that it is driven by the interplay among multiple high-frequency modes. Notably, we identify 1510 cm^-1 as the leading tuning mode that brings the porphyrin to an optimal geometry for energy surface crossing. By employing coherent wave packet analysis, we highlight a set of short-lived vibrations (1200-1400 cm^-1), promoting the IC within ≈60 fs. Furthermore, we identify one coupling mode (1350 cm^-1) that is responsible for vibronic mixing within the Q states. Our findings indicate that porphyrin-core functionalization modulates IC effectively, offering new opportunities in photocatalysis and optoelectronics.

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