ECTS - University of Pisa
Le conoscenze acquisite dagli studenti e dalle studentesse saranno puntualmente verificati durante l'anno tramite discussioni e approfondimenti in classe. L'esame finale è orale e può includere la preparazione di brevi seminari di approfondimento.
The acquired knowledge is assessed all during the year by stimulating the participation of the students in scientific class discussion. The final exam is based on an oral test and can include the preparation of short seminars.
Alla conclusione del corso gli studenti e le studentesse avranno acquisito la capacità di analizzare problemi di ottica che coinvolgono nanomateriali, sia per l'analisi delle proprietà su scala locale che per lo sfruttamento delle specifiche caratteristiche ottiche in dispositivi e metodi. Inoltre riceveranno nozioni di base di nanofotonica e microscopia a scansione di sonda anche non ottica.
Pur avendo un carattere prevalentemente fisico di base, il corso favorisce lo sviluppo di capacità inter-disciplinari, strettamente connesse con altri settori, in particolare biofisica e biomateriali.
At the successful completion of the course, the students will gain the ability to analyze problems of optics involving nanomaterials, both for the analysis at the local sclae and for the exploittion of their specific properties in devices and approaches. Furthermore, they will receive a basic knowledge of nanophotonicsa and scanning probe microscopies, including non-optical methods.
Although the major emphasis is put onto the physical aspects, the course fosters the development of cross-disciplinary ablilities, directly connected with other scientific areas, including, e.g., biophysics and biomaterials.
Durante il corso gli studenti sono incoraggiati a discutere gli aspetti di maggior interesse nel corso delle lezioni. Inoltre le capacità acquisite possono essere verificate anche attraverso la preparazione di brevi presentazioni su argomenti inerenti il corso.
During the course, students are required to play a pro-active role in discussing topics of their interest. Moreover, the ablities can be assessed also through the preparation of short presentations on selected topics.
Gli studenti e le studentesse acquisiranno sensisbilità specifica nel trattare argomenti di nanomateriali da un punto di vista interdisciplinare, che, partendo dalle proprietà fisiche di base, arriva alle applicazioni attuali e di maggior risonanza.
Students will gain specific skills in the cross-disciplinary approach to nanomaterials that, starting from the fundamental physical basis, leads to emerging applications at the state-of-the-art.
L'atteggiamento di apertura interdisciplinare degli studenti sarà verificato durante le discussioni in classe, anche attraverso specifici test basati su brevi presentazioni.
The cross-disciplinary skills will be verified during the class discussions, also thorugh specific tests based on short presentations.
Conoscenze base di elettromagnetismo e fisica dei materiali, incluse basi di meccanica quantistica.
Electromagnetism and material physics, including basic elements of quantum mechanics.
Descrizione dei livelli energetici vibrazionali e rotazionali delle molecole e loro regole di selezione.
Descrizione dei livelli energetici nei solidi isolanti (centri di colore, terre rare, metalli di transizione) e semiconduttori (elettroni, fononi, eccitoni…)
Cenni di teoria dei gruppi applicata alla classificazione dei livelli vibrazionali delle molecole.
Tecniche sperimentali per misure di assorbimento, emissione, vite medie, spettroscopia Raman, spettroscopia di Fourier: reticoli di diffrazione, monocromatori, interferometri, sorgenti e rivelatori
Scopi e motivazioni per la spettroscopia di nanomateriali, proprietà specifiche di nanostrutture inclusi fenomeni biomimetici, aspetti tecnologici. Microscopia elettronica come riferimento per l'analisi del nano-mondo: configurazioni strumentali generali di SEM e TEM, principali meccanismi di contrasto, spettroscopie (AES, EDS/EDAX, XPS).
Richiami di ottica geometrica, fasci Gaussiani, diffrazione e interferenza; cenni di ottica di Fourier, PSF e potere risolutivo (criteri di Rayleigh, Abbe, Sparrow). Microscopia ottica convenzionale e varianti (polarizzazione, DIC, white-light profilometry). Microscopia di fluorescenza, cromofori e richiami di livelli molecolari e transizioni, applicazioni biofisiche, problematiche di illuminazione, dark-field microscopy. Raman, Raman coerente (SRS, CRS, CARS), esempi di misure alla nanoscala su vari materiali.
1. Generalities on the topic
Aims and motivations for spectroscopy of nanomaterials, specific properties of nanostructures including biomimetics, size limits of the nanoworld, technological issues. The main problem of optics in the nanoworld: interference and diffraction in optics. Electron microscopy as a benchmark and a reference for nanoscopy: general instrumental configurations of SEM and TEM, main contrast mechanisms, secondary and backscattered electrons. Spectroscopies with electrons/X-rays: AES, EDS/EDAX, XPS.
2. Optical microscopy/spectroscopy and nanomaterials
Ray optics, lenses and magnification in a microscope, Gaussian beams and focusing, diffraction and interference. Few words on Fourier optics: PSF and resolving power according to Rayleigh, Abbe, and Sparrow criteria. Conventional optical microscopy and some variants: polarization, differential interference, white light profilometry. Fluorescence microscopy, organic chromophores, reminders of molecular levels and transitions, biophysical applications: epi-fluorescence, illuminations issues, dark field microscopy. Confocal configurations of optical microscopy/spectroscopy, examples. MicroRaman, coherent Raman (CRS/CARS) and other advanced spectroscopies at the micro-scale, examples and measurement of various material properties at the micro- and nanoscale.
3. Super-resolution optical microscopies
Stimulated emission in a multi-level system, pumping and saturation. Spiral phase plates, optical vortices, doughnut modes. STED, resolving power, examples of applications. Other super-resolved microscopies (PALM, STORM, 4Pi, light-sheet, double beam, etc.)
4. Quantum confinement and optical properties of semiconductor nanostructures
Reminders of bulk semiconductor properties, direct and indirect transitions. Reminders of quantum mechanics and the problem of the potential well (infinite and finite). Confinement and 2-D (quantum wells), 1-D (quantum wires), 0-D (quantum dots) nanostructures: quasi-discrete levels, interband and intraband transitions, sub- and mini-bands, excitons in confined systems, density of states and dimensionality. Absorption and emission properties in quantum dots, including core-shell systems, related technologies and some applications, in particular in optical nanoscopy and nano-photonics.
5. Plasmonics at a surface
Introduction to plasmonics: plasma frequency in metals and bulk plasmons, interband transitions and their role, complex dielectric constant and refractive index, Drude model. Surface plasmon polaritons at plane interfaces: solution of the electromagnetic problem leading to longitudinal e.m. waves stemming from surface charge oscillations, evanescent behavior and dispersion relation. Excitation of plasmon modes: through evanescent waves, including near-fields, gratings, high aperture objectives (TIRF microscopy). Visualization of plasmon modes via leakage microscopy (Fourier plane imaging) and collection-mode near-field microscopy. Surface plasmon spectroscopy and applications. Main optical properties of graphene and plasmonics in graphene: examples with apertureless near-field microscopy.
6. Plasmonics at a nanoparticle
Emission of radiation in the far-field from oscillating dipoles according to the Maxwell equations, Larmor’s formula. Scattering from nanostructures: dipole and multipole contributions (Rayleigh and Mie); Clausius-Mossotti expression of dielectric constant. Localized surface plasmon resonances, optical extinction, dispersion relation, a few words on geometrical issues (beads, wires and other shapes): role of localized plasmon resonances in optics and photonics, plasmonic nanostructures as markers in microscopy, sensing applications, a few words on plasmon-based therapeutics, local field enhancement and the concept of nano-antennas, transfer of e.m. energy through plasmonic waveguides. SERS-active substrates for enhanced Raman spectropcopies: examples.
7. Photonic band-gap structures and metamaterials
Bragg interference in planar and non-planar structures, transmission and reflection, occurrence of a photonic band-gap: similarities with the electron wavefunctions in solid-state materials and with the energy gap in crystalline semiconductors. Survey of photonic band-gap nanostructures in one and two dimensions, including fabrication. Examples of applications: photonic crystal fibers and super-continuum generation, waveguides and photonic components, optical spectroscopies, laser cavities. Basics of metamaterials: tuning the e.m. properties of a system through structural engineering, control of the magnetic permeability, single and double negative materials, negative refractive index; open possibilities and perspective applications of metamaterials in different fields.
8. Scanning probe microscopies for the spectroscopy of nanomaterials: STM
Concepts and basic elements of SPMs: piezoelectric scanners and probes, the invention of STM and the role of feedback. Reminders of tunnel effect including semi-classical approximations for trapezoidal barriers, role of material properties (work function) and related spectroscopies, examples. Advanced quantum pictures of tunneling: role of local density of states and bias-based spectroscopies, s- and p-wave tunneling and functionalized probes, observation of “molecular orbitals” in isolated molecules, examples including UHV and low-temperature STM.
9. AFM and some variants
Measurement of small forces through a cantilever and optical lever, technology of AFM probes. Forces between a tip and a surface: general considerations, Hertzian contact, Hamaker attraction. Operating modes of an AFM: contact vs tapping mode, modulation/demodulation (amplitude, phase, frequency), phase maps and their physical interpretation (in intermittent contact), constant amplitude and multi-modal AFM. Examples, including in liquid operation, and related force spectroscopies. Lateral forces and nanotribology, electric and piezoelectric force microscopy with examples, nanoindentation and spectroscopies for the investigation of mechanical properties at the nanoscale.
10. Optical near-fields and SNOM
General concepts of near-field, calculation of the near-field produced by an oscillating dipole, ideal problems (Bethe-Bouwkamp), evanescent character and practical implementations. Basics of near-field microscopy in the emission mode: probes and related technologies, the shear-force method, range of spectroscopies accessible by SNOM, including collection mode of operation. Examples of fluorescence and label-free spectroscopy with biological materials, applications to surface and localized plasmons. Polarization-modulated spectroscopies and applications in the near-field. Apertureless (scattering) SNOM: pros and cons, single molecule fluorescence, IR spectroscopy in the near-field, a few words on THz SNOM. Tip-enhanced Raman spectroscopy and examples of TERS.
La bibliografia specifica per ogni argomento trattato, inclusi anche articoli di ricerca, à comunicata agli studenti e studentesse al termine delle lezioni.
The relevant and specific bibliography for every topic of the course, including also research papers, is communicated to the students at the end of the lectures.
Mettersi in contatto preliminarmente con i docenti e seguire il materiale didattico fornito via web.
To contact preliminarly the lecturers and visit the relevant web pages for the didactical materials.
Esame finale orale, parte del quale può essere sostenuta basandosi su una breve presentazione su argomento concordato (tipicamente un recente sviluppo sperimentale di spettroscopia dei nanomateriali).
Oral final exam, partly fulfilled through a short presentation on a topic chosen in agreement with the lecturers (typically, a recent advancement in the field).
Ulteriori informazini sul corso sono reperibili alle seguenti pagine web:
http://osiris.df.unipi.it/~toncelli/didattica/M&NT/spectroscopy.html
pagina di e-learning per il secondo modulo del corso
Further info are available at
http://osiris.df.unipi.it/~toncelli/didattica/M&NT/spectroscopy.html
e-learning page of the second module of the course
