Electromagnetic Field-Dressed Diabatic and Adiabatic Potential Energy Curves

5 Electromagnetic Field-Dressed Diabatic and Adiabatic Potential Energy Curves 

Most of the experiments discussed in this book are performed using continuous wave or nanosecond-pulsed lasers at I 109 W/cm2 intensities, which correspond to electromagnetic radiation electric field strengths of 9 x 105 V/cm. Such electric fields are weak relative to typical intramolecular field strengths, ° = 1 a.u. = 5.14 x 109 V/cm and are appropriately treated perturbatively (see Sections 6.1.2 and 6.5.3). 

When experiments are performed in the intense I 1011 W/cm2 electromagnetic fields typically provided by picosecond or femtosecond pulsed lasers, it is necessary to solve the time-dependent Schrodinger equation in a non-perturbative approach (see Section 9.1.2). The total Hamiltonian is 

It is convenient to treat intense electromagnetic field problems in the dressed molecular states picture (see review by Giusti-Suzor, et al, (1995)). This picture allows one to think about intense field problems in a framework that closely resembles the weak field, diabatic or adiabatic states picture that is the primary focus of this book. In the dressed states picture the photon energy is added to, or subtracted from, the field-free potential energy curves. One obtains field-dressed potential curves. 

The electromagnetic radiation field is taken into account by adding the energy of the photons to the various molecular potential curves, Vi(R). If the photon number is initially N, when n photons are absorbed, the remaining number of photons is N — n. The resultant field-dressed diabatic state has potential energy 

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