Excited-state intermolecular proton transfer of firefly luciferin V. Direct proton transfer to fluoride and other mild bases

We studied the direct proton transfer (PT) from electronically excited D-luciferin to several mild bases. The fluorescence up-conversion technique is used to measure the rise and decay of the fluorescence signals of the protonated and deprotonated species of D-luciferin. From a base concentration of 0.25 M or higher the proton transfer rates to the fluoride, dihdyrogen phosphate or acetate bases are fast and comparable. The fluorescence signals are nonexponential and complex. We suggest that the fastest decay component arises from a direct proton transfer process from the hydroxyl group of D-luciferin to the mild base. The proton donor and acceptor molecules form an ion pair prior to photoexcitation. Upon photoexcitation solvent rearrangement occurs on a 1 ps time-scale. The PT reaction time constant is ～2 ps for all three bases. A second decay component of about 10 ps is attributed to the proton transfer in a contact pair bridged by one water molecule. The longest decay component is due to both the excited-state proton transfer (ESPT) to the solvent and the diffusion-assisted PT process between a photoacid and a base pair positioned remotely from each other prior to photoexcitation.     

Mind Stuffed with Red Herrings: Why William James’ Critique of the Mind-Stuff Theory Does not Substantiate a Combination Problem for Panpsychism

There is a famous passage in chapter six of James’ Principles of Psychology whose import, many believe, deals a devastating blow to the explanatory aspirations of panpsychism. In the present paper I take a close look at James’ argument, as well as at the claim that it underlies a powerful critique of panpsychism. Apart from the fact that the argument was never aimed at panpsychism as such, I show that it rests on highly problematic assumptions which, if followed to their logical consequences, are just as inedible to contemporary critics of panpsychism as they are to its present-day supporters. Hence, a naïve employment of the argument, as a critique leveled by physicalists against panpsychism, is counterproductive and even self-defeating. After examining the metaphysical shortcomings undermining James’ position (as well as the hasty “refutations” of panpsychism based on it), I conclude with some reflections on what needs to be done in order to obtain a better perspective regarding the explanatory prospects of panpsychism as an alternative approach to mainstream physicalism in the study of conscious phenomena.