The properties of transition metal clusters differ from those of both atomic and bulk size regimes. Such clusters are incompletely understood and potentially useful, making them attractive targets for further study. The very smallest clusters studied in this thesis (CuO, Cu₂ and Cu₃) have been investigated with velocity map imaging. 1+1' photodissociation of CuO X ²Π_3/2 was observed, via the C, D, E, F and H states of CuO. CuO* was photodissociated to form Cu(²D_3/2) + O(¹D₂). D₀(CuO) was determined to be 3.041±0.030 cm^-1. Non-resonant three-photon Cu₂ photodissociation occurred throughout the energy range studied to produce one ground-state and one highly-excited copper atom,Cu*. Cu* was ionised by a single additional visible photon. Nearly all Cu* atoms with internal energies between 41000 and 53000 cm^-1 were observed. D₀(Cu₂) has been calculated to be 1.992±0.037 eV. Features arising from photodissociation of Cu₃ were observed in the Cu^+ and Cu₂^+ ion yield spectra and images. Their structure was ill-resolved due to uncertainties in the internal energy of both parent Cu₃ and product Cu₂. These features correspond to single-photon dissociation of Cu₃ to produce metastable D-states of the copper atom and vibrationally excited Cu₂. One series of features implies a previously-unobserved state of either Cu₂ or Cu₃. Rh_nN₂O^+ and Rh_nON₂O^+ (n=5, 6) were collisionally activated in collision-induced dissociation (CID) experiments with Ar and ¹³CO. These experiments were carried out in a Fourier Transform Ion Cyclotron Resonance(FT-ICR)spectrometer. Argon collisions induced both N₂O desorption and N₂O reduction. The branching ratios observed reproduced those seen in prior IR-MPD experiments. ¹³CO was observed to chemisorb to the cluster upon collision, activating not only N₂O desorption and reduction but also CO oxidation. Formation of CO2 was noted to be particularly rapid on the n=5 cluster compared to the n=6 cluster. Reactions of Rh_nN₂O^+ (n=4-6) clusters were also activated by black body radiation. This technique is known as BIRD - black-body induced infrared radiative dissociation. These studies revealed that the N₂O desorption barrier exceeds the N₂O reduction barrier on all clusters studied, but that the entropic favourability of desorption increases its rate relative to reduction with increasing cluster internal energy. The BIRD rate was much reduced upon cooling the ICR cell to 100 K. A further test of the BIRD mechanism increased the number of N₂O ligands and hence the absorption rate. An approximately linear increase in the dissociation rate of Rh_n(N₂O)_m^+ was observed with index m. Deviations from linearity were caused by variations in the N₂O desorption rate. In the case of Rh₅(N₂O)_m^+, desorption rates corresponded closely to N₂O binding energies calculated by density functional theory. The system was modelled using a master equation approach.

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