Non-stationary states in chemistry

After a brief introduction on the theoretical area concerning the propagation of non-stationary states, two examples of our activity in the field of time-dependent processes are presented and discussed. The first concerns the possibility of controlling photochemical and photophysical processes by properly shaped, short, weak laser pulses. A theoretical approach developed in our group is briefly reviewed and a new example is presented on the control of the energy deposition in a model linear aggregate of ten chromophores. The second example deals with hydrogen transfer in DNA base pairs and presents the result of a time-dependent calculation on adenine-thymine and guanine-cytosine pairs. These calculations show a coherent, periodic behaviour and put in evidence that the imino-enol tautomerism cannot be interpreted as a source of mutations, since it would generate too many mutation points along the DNA.