Laboratory experiments using the instrument RAPID (Bruker) have been performed in order to compare the performance with one of the previously evaluated instrument, OPAG 22 (Bruker), to add more spectra to the instrument library and to gain more experience from the instrument. Seven different substances were tested and four of them (DIMP, TBP, GA, GF) were detected from the measured gas phase spectra. The other three (HN1, HN2, Sesqui mustard) turned out to be difficult to generate in gas phase. The detection limit of these substances is in the range of 0.1-2 mgm-3 with a cloud thickness of 100 meters and a temperature difference between the background and the cloud of 1oC. This is about a factor 2-10 less sensitive than the detection limits achieved using OPAG 22. This report also presents results from a study of the apparent temperature difference between ambient air and the background in Swedish terrain. The temperature difference is crucial for passive remote detection and IR data have been analysed in the spectral band 8-12 microm. The probability for a temperature difference of 2oC or more was found to be 0.3 for cut grass and 0.2 for forest. Two models relating the apparent temperature difference to weather parameters are presented, one based on linear regression and one semi-empirical based on basic physical principles, the latter producing the best agreement with measurements giving a deviation of 1-2 oC in most cases.