Electrical Control of Optical Emitter Relaxation Pathways enabled by Graphene

Controlling the energy flow processes and the associated energy relaxation rates of a light emitter is of high fundamental interest, and has many applications in the fields of quantum optics, photovoltaics, photodetection, biosensing and light emission. While advanced dielectric and metallic systems have been developed to tailor the interaction between an emitter and its environment, active control of the energy flow has remained challenging. Here, we demonstrate in-situ electrical control of the relaxation pathways of excited erbium ions, which emit light at the technologically relevant telecommunication wavelength of 1.5 $\mu$m. By placing the erbium at a few nanometres distance from graphene, we modify the relaxation rate by more than a factor of three, and control whether the emitter decays into either electron-hole pairs, emitted photons or graphene near-infrared plasmons, confined to $<$15 nm to the sheet. These capabilities to dictate optical energy transfer processes through electrical control of the local density of optical states constitute a new paradigm for active (quantum) photonics.Comment: 9 pages, 4 figure

La localizzazione dei servizi alle famiglie nella Lombardia Orientale.

Taormin

Femtosecond stimulated Raman spectrometer in the 320-520nm range

Multi-mu J narrow-bandwidth (approximate to 10 cm(-1)) picosecond pulses, broadly tunable in the visible-UV range (320-520 nm), are generated by spectral compression of femtosecond pulses emitted by an amplified Ti:sapphire system. Such pulses provide the ideal Raman pump for broadband femtosecond stimulated Raman spectroscopy, as here demonstrated on a heme protein. (C) 2011 Optical Society of Americ

Broadly Tunable Narrowband Pump Pulses for Femtosecond Stimulated Raman Spectroscopy

Using spectral compression by second-harmonic generation we generate pulses with 10 divided by 15 cm(-1) linewidth, multi-mu J energy and broad tunability from 330 to 510 nm. This source is ideally suited as Raman pump for Stimulated Raman Scattering. (C) 2010 Optical Society of Americ

BISLAM. Bibliotheca Scriptorum Latinorum Medii Recentiorisque Aevi / Repertory of Medieval and Renaissance Latin Authors. I. Gli Autori in \uabMedioevo Latino\ubb / Authors in \uabMedioevo Latino\ubb

BISLAM \ue8 una nuova collana di strumenti utili all'identificazione e alla lemmatizzazione degli autori latini del Medioevo. Disponibile in CD-ROM + volume a stampa, questo primo repertorio della serie, Gli Autori in "Medioevo latino", \ue8 costituito dall'elenco delle diverse forme nominali con le quali gli autori erano e sono conosciuti, oltre che da una serie di elementi identificativi e bibliografici. Comprende quasi 5.300 voci che corrispondono agli autori lemmatizzati nei primi ventuno volumi pubblicati del repertorio bibliografico "Medioevo latino". Esso si propone come authority list, vale a dire come un elenco di voci di autorit\ue0, controllate sulla base della bibliografia pi\uf9 recente e affidabile e costituite secondo norme uniformi. Di ogni autore medievale viene quindi fornita una forma del nome, prescelta in base a criteri storici, bibliografici e filologici, e tutte le sue principali varianti. Oltre alle forme nominali, ciascuna voce contiene un riferimento alle schede di "Medioevo latino" che segnalano studi sull'autore o edizioni delle sue opere, svolgendo in questo modo anche la funzione di indice complessivo per autore di questo bollettino bibliografico. BISLAM I fa parte integralmente dell'opera BISLAM2 edita nel 2010

Vibrational contrast imaging and nanospectroscopy of single cell membranes by tip enhanced absorption in the mid IR

The ability to perform chemical identification at the nanoscale is crucial for the study of inhomogeneous materials as well as biological matter, and it can be achieved combining mid infrared Mid IR vibrational spectroscopy with the nanometer resolution provided by atomic force microscopy AFM . Recently, a novel route to Mid IR nanoscopy that allows for a direct measurement of the absorption coefficient of few molecular layers has been introduced [1,2]. In this work we apply this novel Mid IR tip enhanced absorption spectroscopy to perform vibrational imaging and nanospectroscopy of single purple membranes, i.e. cell membranes densely filled with bacteriorhodopsin bR , a protein acting as a proton pump across the cell membrane of Halobacteri

Nanospectroscopy of single purple membranes by mid IR resonantly enhanced mechanical photoexpansion

We present mid-infrared vibrational spectroscopy and imaging at the nanoscale of individual cell membranes deposited on ultraflat gold substrate by use of resonantly-enhanced mechanical photoexpansion technique. This platform allows one to measure the energy absorbed by the sample by monitoring its local thermal expansion with a nanometer atomic force microscope tip. The observed Amide-I and Amide-II bands of proteins in the spectrum acquired on individual purple membrane flakes, filled with bacteriorhodopsin (bR) molecules, are in good agreement with the far-field infrared spectrum collected on large numbers of membranes. Differences among the relative intensity of the two Amide bands in the near- and far-field spectra are attributed to different orientation of bR protein molecules in the two samples. Strong vibrational contrast imaging at the Amide-I of proteins with a lateral resolution of around 50 nm is reported for individual flakes of both purple membranes and artificial lipid vesicles loaded with channelrhodospin molecules

Phonon-mediated mid-infrared photoresponse of graphene

The photoresponse of graphene at mid-infrared frequencies is of high technological interest and is governed by fundamentally different underlying physics than the photoresponse at visible frequencies, as the energy of the photons and substrate phonons involved have comparable energies. Here, we perform a spectrally resolved study of the graphene photoresponse for mid-infrared light by measuring spatially resolved photocurrent over a broad frequency range (1000-1600 cm-1). We unveil the different mechanisms that give rise to photocurrent generation in graphene on a polar substrate. In particular, we find an enhancement of the photoresponse when the light excites bulk or surface phonons of the SiO2 substrate. This work paves the way for the development of graphene-based mid-infrared thermal sensing technology