Calibration of the length of a chain of single gold atoms

Using a scanning tunnelling microscope or mechanically controllable break junction it has been shown that it is possible to control the formation of a wire made of single gold atoms. In these experiments an interatomic distance between atoms in the chain of ∼3.6 Å was reported which is not consistent with recent theoretical calculations. Here, using precise calibration procedures for both techniques, we measure the length of the atomic chains. Based on the distance between the peaks observed in the chain length histogram we find the mean value of the interatomic distance before chain rupture to be 2.5±0.2 Å. This value agrees with the theoretical calculations for the bond length. The discrepancy with the previous experimental measurements was due to the presence of He gas, that was used to promote the thermal contact, and which affects the value of the work function that is commonly used to calibrate distances in scanning tunnelling microscopy and mechanically controllable break junctions at low temperatures.

Determinant factors of senior tourists’ length of stay

The current tendency to undertake more trips, but of shorter duration, throughout the year, has meant that the tourist industry has started to show greater interest in attracting those market segments that opt for more prolonged stays, as they are especially profitable. One of these segments is that of seniors. Given the aging demographic of the population worldwide, which is particularly noticeable in Spain, the object of this study is to identify the variables that determine the length of stay of Spanish seniors at their destination. The Negative Binomial model was adapted to the context of length of stay by Spanish seniors and the determinant factors identified were: age, travel purpose, climate, type of accommodation, group size, trip type and the activities carried out at the destination. This study is a contribution to this field from an empirical point of view, given the scarcity of studies of this type and their eminently descriptive character; as well as from a practical level, with interesting implications for the sector.