We present a minimal analytical bound-continuum model for resonance-enhanced two-photon ionization of atomic hydrogen by chirped pulses, highlighting chirp-induced nonadiabatic coupling in Autler-Townes (AT) splitting. The model incorporates the $1s$–$2p$ bound transition, couplings to $s$- and $d$-wave continua, chirp-dependent detuning, dynamic Stark shifts, energy-dependent ionization matrix elements, and ionization decay. We provide closed-form expressions for time-dependent amplitudes and the photoelectron spectrum. The model demonstrates two key principles: the pulse area determines the number of AT peaks via time-domain interference, and chirp induces nonadiabatic coupling between dressed states, characterized by a single complex parameter $\alpha \left(t\right)$ that breaks spectral symmetry. Comparisons with three-dimensional time-dependent Schrödinger equation simulations validate the model's accuracy across a wide chirp range. This framework analytically links control parameters to spectral observables and is adaptable to other systems.

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• Coherent control
• Electronic excitation & ionization
• Strong field ionization & excitation
• Atoms
• Polarizability
• Rotating wave approximation
• Schroedinger equation