Time-frequency characterization of femtosecond extreme ultraviolet pulses

A measurement of chirp and pulse duration of fifth harmonic of a frequency-doubled Ti:sapphire laser was presented. The photoelectron signal due to cross correlation of harmonics generated by 400 nm blue light and an 800 nm infrared probe pulse, was measured using energy resolved cross-correlation method. Results demonstrated that the technique could be used to characterize the time-frequency behavior of much higher-order harmonics

Time-Frequency Characterization of Femtosecond Extreme Ultraviolet Pulses

A measurement of chirp and pulse duration of fifth harmonic of a frequency-doubled Ti:sapphire laser was presented. The photoelectron signal due to cross correlation of harmonics generated by 400 nm blue light and an 800 nm infrared probe pulse, was measured using energy resolved cross-correlation method. Results demonstrated that the technique could be used to characterize the time-frequency behavior of much higher-order harmonics

Time-frequency characterization of femtosecond extreme ultraviolet pulses.

We present energy-resolved cross-correlation measurements of an extreme ultraviolet (XUV) pulse, generated as the fifth harmonic (15.5 eV) of an intense 80 fs laser pulse centered at 400 nm. Spectrally resolving the cross-correlation signal allows us to characterize the time-dependent frequency of the XUV pulse. We find that the fifth harmonic has a small negative chirp in excess of that predicted by perturbation theory. In addition, by manipulating the chirp of the driving laser we can induce and measure a positive or a negative chirp on the XUV pulse

From the Governance of Sustainability to the Management of Climate Change: Reshaping Urban Policies and Central–local Relations in France

This paper analyses the interlinked usages of the concepts of ‘governance’ and ‘sustainable development’ over the past two decades of French urban policies. It shows that the importance of ‘sustainable development’ procedural principles has significantly declined in public agendas alongside the rise to prominence of climate change issues. Based on a study of the urban policies developed by central French government authorities since the 1990s, it identifies two main phases. In the 1990s and early 2000s, ‘sustainable development’ and ‘governance’ slogans were extensively mobilized in urban policies for the purposes of modernizing public action. In a context of economic, social and institutional transformations, these urban policies aimed at constructing local dynamics of collective action and encouraged the emergence of projects relying on incremental and deliberative practices. As of the mid-2000s, this dynamic weakened and climate change replaced sustainable development as a reference in urban policies. This shift occurred in the context of a neo-managerial restructuring, with central government authorities regaining influence over cities and urban policies being redefined around quantitative and technical objectives