Li(NH(3))(4) has been proposed as a key entity in lithium-ammonia solutions, but its spectral signature has so far proved impossible to distinguish from other species in these solutions. Here we report the first electronic spectrum of Li(NH(3))(4) in the gas phase, which was recorded using mass-selective depletion spectroscopy. Strong absorption is observed in the near-infrared and the band system is assigned to the A (2)T(2)-X (2)A(1) transition in a nominally tetrahedral complex. However, the vibrational structure is indicative of a substantial Jahn-Teller effect in the excited electronic state. The broad and structured spectrum confirms a recent theoretical prediction that the electronic spectrum of Li(NH(3))(4) will strongly overlap with the spectrum of the solvated electron in lithium-ammonia solutions.

Electronic spectra of LiNH 3 and its partially and fully deuterated analogues are reported for the first time. The spectra have been recorded in the near-infrared and are consistent with two electronic transitions in close proximity, theà 2 E−X 2 A 1 andB 2 A 1 −X 2 A 1 systems. Vibrational structure is seen in both systems, with the Li-N-H bending vibration (ν 6 ) dominant in theà 2 E−X 2 A 1 system and the Li-N stretch (ν 3 ) in theB 2 A 1 −X 2 A 1 system. The prominence of the 6 1 0 band in theà 2 E−X 2 A 1 spectrum is attributed to Herzberg-Teller coupling. The proximity of theB 2 A 1 state, which lies a little more than 200 cm −1 above theà 2 E state, is likely to be the primary contributor to this strong vibronic coupling.

Artificial intelligence (AI) is producing highly beneficial impacts in many domains, from transport to healthcare, from energy distribution to marketing, but it also raises concerns about undesirable ethical and social consequences. AI impact assessments (AI-IAs) are a way of identifying positive and negative impacts early on to safeguard AI’s benefits and avoid its downsides. This article describes the first systematic review of these AI-IAs. Working with a population of 181 documents, the authors identified 38 actual AI-IAs and subjected them to a rigorous qualitative analysis with regard to their purpose, scope, organisational context, expected issues, timeframe, process and methods, transparency and challenges. The review demonstrates some convergence between AI-IAs. It also shows that the field is not yet at the point of full agreement on content, structure and implementation. The article suggests that AI-IAs are best understood as means to stimulate reflection and discussion concerning the social and ethical consequences of AI ecosystems. Based on the analysis of existing AI-IAs, the authors describe a baseline process of implementing AI-IAs that can be implemented by AI developers and vendors and that can be used as a critical yardstick by regulators and external observers to evaluate organisations’ approaches to AI.

We report the first spectroscopic study of a complex consisting of a rare earth atom in combination with ammonia. Using two-color resonance-enhanced multiphoton ionization (REMPI) spectroscopy, the lowest energy electronic transition of YbNH 3 has been found in the near-infrared. The spectrum arises from a spin-forbidden transition between the 1 A 1 ground electronic state and the lowest 3 E excited electronic state. The transition is metal centered and approximately correlates with the Yb 6s6p 3 P ← 6s 2 1 S transition. The observation of clear spin-orbit structure in the spectrum confirms the C 3v symmetry of YbNH 3 . Vibrational structure is also observed in the REMPI spectrum, which is dominated by excitation of the Yb-N stretching vibration.