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The available experimental data provided by ultrafast dynamics studies of pyrrole and its derivatives in excited states of mixed Rydberg/valence 3s/πσ* character are strongly affected by the interaction with the laser pulses. Understanding these data has constituted an endeavor for several groups during the past few years. Here we apply a simple theoretical model that, including the interaction with the laser pulses, allows one to clarify some aspects of the discrepancies between measurements monitoring different experimental observables. New experimental data on pyrrole, 2,4-dimethylpyrrole, and 2,5-dimethylpyrrole are also provided to check the validity of the model and to gain more insight into the excited state dynamics of pyrrole systems.

A detailed investigation on the ion kinetic energy distributions of ions ejected in the nanosecond pulsed laser ablation of aluminum is reported. For laser fluences just over threshold, the emerging ions fit shifted neat Maxwell−Boltzmann-Coulomb (MBC) distributions. For fluences higher than ∼1.3 J/cm 2, the Al +distributions split into two MBC contributions peaked at different energies. It is demonstrated that the observed Al +ion distribution has two components, one fast, correlated with the direct multiphoton laser ionization, and the other slow, associated with electron−Al 0collisions in the solid. A similar behavior is observed at higher fluences for all Al ion distributions indicating that the electron-impact ionization of Al rate constants is faster than that of recombination and other possible collision channels. In addition, the linear relationship between the Coulomb velocities and the ion charges and the behavior of Coulomb energy of the ions versus the laser fluence suggest the appearance of an electric field within the metal/laser interaction volume that impels the ions up to the high velocities measured. A discussion of the application of this type of mechanisms to other metals is advanced.

This work reports the identification of the gas phase amino-p-phenethylamine (APEA) conformers with computed DFT stable structures. Two-colour mass-resolved multiphoton ionisation and hole burning spectroscopies have been used to find the number of conformers and record their spectra. The spectra show the presence of four well-characterized conformers, with origin bands paired off as gauche and anti conformers, in clear contrast to the five stable structures predicted by computational methods. Several criteria have been employed to relate the experimental spectra of the conformers to stable computed structures, the ionisation energies being the most reliable for unambiguous identification. The method can be applied to other small- and medium-size biological and organic molecules.

A computational investigation of the hydrated complexes of p-methoxyphenethylamine(H2O)2-4 (hereafter referred to as either MPEA(H2O)2-4 or simply 1:2−4) has been conducted at the B3LYP/6-31+G* level in order to find out the stable structures and the isomer binding energies (BEs). As expected, the calculations supply a large number of stable geometries, built up from one of the seven MPEA conformers and a chain of solvent molecules attached to a number of sites of the chromophore molecule. Within each complex stoichiometry, some isomers have very close binding energies, in fact, smaller than that of the basis set superposition error (BSSE). Despite the seven MPEA conformer precursors, the number of complex isomers recognized in two-color mass-resolved time-of-flight (TOF) and “hole burning” spectra are scarce:  one for both 1:2 and 1:3 complexes, and two for the 1:4 complex. Notwithstanding the difficulty to identify the participant conformer within a specific complex, the computation shed light on a number of significant features of their structures, for example, that the first water molecule is always bound to the nitrogen atom of the NH2 group; in the 1:2 complex, the last arrived solvent attaches to the water already bound and to the hydrogen atom of the NH2 pointing away from the aromatic ring; the addition of the third solvent results in the formation of a water daisy chain around the NH2 moiety, and the addition of the fourth water gives rise to two structures of close stability. These results are interpreted as the systematic presence of two isomers for all 1:1−4 complexes but that their spectra overlap for 1:2 and 1:3 at the resolution of the experiments. The calculated energies for the addition of one water molecule at a time to the 1:n complex match fairly well the experimental measurements (within ~200−300 cm^-1, <1 kcal/mol).

Binding or dissociation energies of the ground state, S0, the first electronic excited state, S1, and the ion ground state, I0, of the p-methoxyphenetylamine(H2O)1-4 complexes, referred to henceforth as either MPEA(H2O)1-4 or by their stoichiometric ratios 1:1−4, have been analyzed by threshold ion fragmentation. MPEA(H2O)1-4 complexes were prepared by the supersonic expansion of premixed samples containing appropriate amounts of MPEA and water molecules into carrier gas He. A number of isomers, with characteristic %@mt;sys@%0%@sx@%0%@be@%0%@sxx@%%@mx@% transition energies, have been identified:  two for MPEA(H2O)1 at 35 676 and 35 689 cm^-1, one for MPEA(H2O)2 at 35 687, one for MPEA(H2O)3 at 35 571 and two for MPEA(H2O)4 at 35 419 and 35 422 cm^-1 respectively. The ionization energy and fragmentation thresholds, the latter defined as the onset energy of the process MPEA(H2O)n* + hν→ MPEA(H2O)n-1⁺ + H2O, have been determined, and from them the dissociation energies for the set of MPEA(H2O)1-4 isomers in their ground state, first electronic excited states, and ion ground states were readily obtained. The set of values are compared with those computed for the water association complexes.

A combined wide range of laser spectroscopic techniques and computational quantum chemistry are used to investigate conformer landscapes of large substituted aromatic molecules. The spectroscopic techniques include laser-induced fluorescence (LIF), high-resolution LIF, resonance-enhanced multiphoton ionization (REMPI) with mass detection, two-color resonance ionization with mass detection (R2PI), laser dispersed emission (DE), and ion-dip hole burning (HB). These techniques are balanced with extensive ab initio DFT calculations at the B3LYP/6-31+G* and B3LYP/6-311+G* levels. These methods have been applied to investigate the nine possible conformations of the p−methoxyphenethylamine (MPEA) neurotransmitter molecule. Even when all the spectroscopic techniques play important roles, two color ionization energy (IE) threshold determinations have proven to be especially useful in the study. The gauche and anti conformers exhibit different ionization energy values, and even the amino hydrogen orientation influences their energies. The results allow the unequivocal identification of seven conformer structures which are further confirmed by the assignment of their vibrational spectra. A discussion on the intramolecular interactions, including the N−H···π hydrogen bonding correlation with the molecular stability in the light of the theoretical and experimental results, is also presented.

With the object of proving whether seqeuntial or alternate forms of chemotherapy would be advantageous one over the other in treating advanced breast cancer and with the purpose of evaluating two different anthracyclines at equimolecular doses in the above-mentioned alternating regimens, 250 patients who had received no prior chemo- or hormonotherapy were entered in a prospective randomized trial. Group A was administered 4-epiadriamycin and cyclophosphamide for 8 courses, followed by 6 cycles of CMF, and medroxyprogesterone acetate (MPA) from the beginning of therapy until progression. In group B, adriamycin + cyclophosphamide were alternated with CMF every two courses until 14 cycles were completed. Group C received 4'-epiadriamycin + cyclophosphamide alternated with CMF for 14 courses. In groups B and C, MPA was administered as in group A. Two hundred and twenty-four patients were evaluated. CR+PR were observed in 55.8 % of group A, 43.4 % of group B, and 46.4 % of group C. Median duration of responses was 16 months (m) in group A, 13 m in group B and 20 m in group C., and median survival (CR + PR) was 16.5 m in group A, 16 m in group B and 24 m in group C. There were no statsitically significant differences among the three groups in terms of response rate, duration of response and survival; furthermore, toxicity was moderate in all groups. At equimolecular doses there were no differences between adriamycin and epirubicin in the alternating schedules.