On the recollision-free excitation of krypton during ultrafast multi-electron tunnel ionization

The probability of multiple ionization of krypton by 50 femtosecond circularly polarized laser pulses, independent of the optical focal geometry, has been obtained for the first time. The excellent agreement over the intensity range 100 TW cm-2 to 100 PW cm-2 with the recent predictions of Kornev et al (2003 Phys. Rev. A 68 043414) provides the first experimental confirmation that non-recollisional electronic excitation can occur in strong-field ionization. This is particularly true for higher stages of ionization, when the laser intensity exceeds 10 PW cm-2 as the energetic departure of the ionized electron(s) diabatically distorts the wavefunctions of the bound electrons. By scaling the probability of ionization by the focal volume, we discuss why this mechanism was not apparent in previous studies.

Solvent-free synthesis of metal complexes

Avoiding the use of solvents in synthesis can reduce environmental contamination and even be more convenient than using solvent-based synthesis. In this tutorial review we focus on recent research into the use of mechanochemistry ( grinding) to synthesise metal complexes in the absence of solvent. We include synthesis of mononuclear complexes, coordination clusters, spacious coordination cages, and 1-, 2- and 3-dimensional coordination polymers ( metal organic frameworks) which can even exhibit microporosity. Remarkably, in many cases, mechanochemical synthesis is actually faster and more convenient than the original solvent-based methods. Examples of solvent-free methods other than grinding are also briefly discussed, and the positive outlook for this growing topic is emphasised.

Efficient, halide free synthesis of new, low cost ionic liquids: 1,3-dialkylimidazolium salts containing methyl- and ethyl-sulfate anions

New low-cost ionic liquids containing methyl- and ethyl-sulfate anions can be easily and efficiently prepared under ambient conditions by the reaction of 1-alkylimidazoles with dimethyl sulfate and diethyl sulfate. The preparation and characterization of a series of 1,3-dialkylimidazolium alkyl sulfate and 1,2,3-trialkylimidazolium alkyl sulfate salts are reported. 1,3-Dialkylimidazolium salts containing at least one non-methyl N-alkyl substituent are liquids at, or below room, temperature. Three salts were crystalline at room temperature, the single crystal X-ray structure of 1,3-dimethylimidazolium methyl sulfate was determined and shows the formation of discrete ribbons comprising of two anion-cation hydrogen-bonded chains linked via intra-chain hydrogen-bonding, but little, or no inter-ribbon hydrogen-bonding. The salts are stable, water soluble, inherently 'chloride-free', display an electrochemical window of greater than 4 V, and can be used as alternatives to the corresponding halide salts in metathesis reactions to prepare other ionic liquids including 1-butyl-3-methylimidazolium hexafluorophosphate.

Will attracting the creative class boost economic growth in old industrial regions? A case study of Scotland

Attracting in-migration of the creative class has been argued by Florida (2002) to be a route to higher economic growth in the era of the knowledge economy. This paper critically evaluates this proposition in relation to old industrial regions using the example of Scotland. The paper presents an assessment of, in the first instance, to what extent there is a shortage of skilled, talented and entrepreneurial individuals and, in the second instance, whether a talent attraction strategy alone can hope to attract such people to Scotland. It is proposed that for most migrants the availability of appropriate economic opportunities is a prerequisite for mobility. However, despite uncertain evidence that place attractiveness is a catalyst to mobility among the so-called creative class, this is not a reason for dismissing talent attraction programmes. Instead it is argued that talent attraction programmes have the potential to contribute to old industrial economies, but their success will be greatest when talent attraction is carefully targeted and based on economic realities rather than the marketing of ethereal conceptions of place attractiveness.

Crinoids for lunch? An unexpected biotic interaction from the Upper Ordovician of Scotland

Specimens of the polyplacophoran mollusk 'Helminthochiton' thraivensis Reed from the Upper Ordovician of southwest Scotland provide rare examples of complete valve series preserved in near life position, albeit as external molds. Application of high-resolution X-ray microtomography to one such specimen has revealed the exceptional preservation of its last meal, which included elements of a crinoid column, in its intestine. The interaction was either predatory or scavenging; extant chitons are not known to be crinoidivorous. This is the earliest direct record of predation or scavenging on crinoids in the fossil record. It is also the first indication that the broad axial canal of primitive crinoids may have contained nutritious tissues. The predatory or scavenging habit of H. thraivensis is consistent with its inferred phylogenetic position as a stem-group aplacophoran and provides new data suggesting an origin of carnivory early in the evolution of this clade.

DNA Reorientation on Au Nanoparticles: Label-Free Detection of Hybridization by Surface Enhanced Raman Spectroscopy

DNA sequences attached to Au nanoparticles via thiol linkers stand up from the surface, giving preferential enhancement of the adenine ring breathing SERS band. Non-specific binding via the nucleobases reorients the DNA, reducing this effect. This change in intensity on reorientation was utilised for label-free detection of hybridization of a molecular beacon.