We present a combined experimental and theoretical study on the radiative lifetime of CO in the a (3)Pi(1,2), v=0 state. CO molecules in a beam are prepared in selected rotational levels of this metastable state, Stark-decelerated, and electrostatically trapped. From the phosphorescence decay in the trap, the radiative lifetime is measured to be 2.63+/-0.03 ms for the a (3)Pi(1), v=0, J=1 level. From the spin-orbit coupling between the a (3)Pi and the A (1)Pi states a 20% longer radiative lifetime of 3.16 ms is calculated for this level. It is concluded that coupling to other (1)Pi states contributes to the observed phosphorescence rate of metastable CO.

PostprintThis is the accepted version of a paper published in Journal of Breath Research. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the original published paper (version of record):Schmidt, F., Vaittinen, O., Metsälä, M., Lehto, M., Forsblom, C. et al. (2013) Ammonia in breath and emitted from skin. Abstract. Ammonia concentrations in exhaled breath (eNH 3 ) and skin gas of 20 healthy subjects were measured on-line with a commercial cavity ring-down spectrometer and compared to saliva pH and plasma ammonium ion (NH + 4 ), urea and creatinine concentrations. Special attention was given to mouth, nose and skin sampling procedures and the accurate quantification of ammonia in humid gas samples. The obtained median concentrations were 688 parts per billion by volume (ppbv) for mouth-eNH 3 , 34 ppbv for nose-eNH 3 , and 21 ppbv for both mouth-and nose-eNH 3 after an acidic mouth wash (MW). The median ammonia emission rate from the lower forearm was 0.3 ng cm −2 minute −1 . Statistically significant (p<0.05) correlations between the breath, skin and plasma ammonia/ammonium concentrations were not found. However, mouth-eNH 3 strongly (p<0.001) correlated with saliva pH. This dependence was also observed in detailed measurements of the diurnal variation and the response of eNH 3 to the acidic MW. It is concluded that eNH 3 as such does not reflect plasma but saliva and airway mucus NH + 4 concentrations and is affected by saliva and airway mucus pH. After normalization with saliva pH using the HendersonHasselbalch equation, mouth-eNH 3 correlated with plasma NH + 4 , which points to saliva and plasma NH + 4 being linked via hydrolysis of salivary urea. Journal of Breath

Detection and analysis of volatile compounds in exhaled breath represents an attractive tool for monitoring the metabolic status of a patient and disease diagnosis, since it is non-invasive and fast. Numerous studies have already demonstrated the benefit of breath analysis in clinical settings/applications and encouraged multidisciplinary research to reveal new insights regarding the origins, pathways, and pathophysiological roles of breath components. Many breath analysis methods are currently available to help explore these directions, ranging from mass spectrometry to laser-based spectroscopy and sensor arrays. This review presents an update of the current status of optical methods, using near and mid-infrared sources, for clinical breath gas analysis over the last decade and describes recent technological developments and their applications. The review includes: tunable diode laser absorption spectroscopy, cavity ring-down spectroscopy, integrated cavity output spectroscopy, cavity-enhanced absorption spectroscopy, photoacoustic spectroscopy, quartz-enhanced photoacoustic spectroscopy, and optical frequency comb spectroscopy. A SWOT analysis (strengths, weaknesses, opportunities, and threats) is presented that describes the laser-based techniques within the clinical framework of breath research and their appealing features for clinical use.

We report on the Stark deceleration and electrostatic trapping of ¹⁴NH (a¹Δ) radicals. In the trap, the molecules are excited on the spin-forbidden A³∏ <- a¹Δ transition and detected via their subsequent fluorescence to the X³∑⁻ ground state. The 1/e trapping time is 1.4 ± 0.1 s, from which a lower limit of 2.7 s for the radiative lifetime of the a¹Δ, v=0, ,J=2 state is deduced. The spectral profile of the molecules in the trapping field is measured to probe their spatial distribution. Electrostatic trapping of metastable NH followed by optical pumping of the trapped molecules to the electronic ground state is an important step towards accumulation of these radicals in a magnetic trap

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