TPR—See Temperature programmed

As NO dissociation produces two atoms from one molecule, the reaction can only proceed when the surface contains empty sites adjacent to the adsorbed NO molecule. In addition, the reactivity of the molecule is affected by lateral interactions with neighboring species on the surface. Figure 4.10 clearly illustrates all of these phenomena [38]. The experiment starts at low temperature (175 K) with a certain amount (expressed in fraction of a monolayer, ML) of NO on the Rh(100) surface. During temperature programming, the SIMS intensities of characteristic ions of adsorbed species are followed, along with the desorption of molecules into the gas phase, as in temperature-programmed desorption (TPD) or temperature-programmed reaction spectroscopy (TPRS) (see Chapter 2). 

The reducibility of platinum should be affected both by SOOI effect (see above) and strong metal-support interaction (SMSI) between platinum and transition metal oxide monolayer. Both mentioned effects were observed by means of temperature-programmed techniques. TPR investigations put in evidence that the reducibility of platinum strongly depended on the type of primary carrier as well as on the type of transition metal monolayer. The results of TPR investigations are presented in Fig. 1 and Table 2. 

Transmission FTIR spectroscopy may be combined with a number of other experimental techniques such as, e.g., temperature-programmed reduction (TPR), oxidation (TPO) or desorption (TPD) of probes monitored by, e.g., frequency response (FR) spectroscopy (see also Sect. 4.2), electron spin resonance (ESR) spectroscopy, etc. 

In TPD experiment, gaseous molecules (atoms) of interest are adsorbed at the surface, at constant temperature. The adsorption is very often performed at ambient temperature, but can be sometimes done at sub-ambient or at elevated temperature. In the modifications of technique such as TPO or TPR, gaseous species are consumed while temperature is increased in a programmed manner. In the case of TPD procedure, desorption of adsorbate is monitored while increasing the solid sample temperature in a controlled fashion while in the case of TPR/TPO, the consumption of active gas is monitored during temperature increase, as explained later in more details (see Sect.4.4). 

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