Ultraviolet Photofragmentation Spectroscopy of Alkaline Earth Dication Complexes with Pyridine and 4-Picoline (4-Methyl pyridine)
Year: 2011
Type: article
Abstract: A detailed experimental and theoretical study has been undertaken of the UV photofragmentation spectroscopy of the alkaline earth metal dications Mg(2+), Ca(2+), and Sr(2+) complexed with pyridine and 4-methyl pyridine (4-picoline). The ion complexes have been prepared using the pick-up technique and held in an ion trap where their internal temperature has been reduced to <150 K. Exposure of the trapped ions to tunable UV laser radiation leads to the appearance of photofragments with intensities that show significant variation as a function of wavelength. For all three metal dications, the resultant spectra show evidence of resolved features. Time-dependent density functional theory (TDDFT) has been used to identify possible electronic transitions that might be present in the [M(pyridine)(4)](2+) complexes (M = Mg, Ca, and Sr) within the wavelength range studied. These calculations show that the spectra are dominated by strong π* ← π and weaker π* ← n transitions localized on the pyridine ligands. The calculations correctly identify those regions of the experimental spectra where UV transitions begin to occur in the complexes and also the wavelengths at which absorption maxima are reached; however, more subtle features of the spectra are difficult to assign with confidence.
DOI: 10.1021/jp112171j
Institutions: University of Nottingham, University of Sussex
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2006464969