'Candle light': Manipulating light and matter at the nanoscale for high-resolution imaging and spectroscopy.

NanoMeta

I have finished the NanoMeta Conference in Seefeld, Austria. I am really inspired by many of the talks given there, thus it is really worthwhile to broadcast it a bit.

The conference is held in the beautiful Seefeld in Tirol area.
You can find the program contents on this website> http://www.nanometa.org/.

I have also made a list of some of my favorite talks or posters during last week> NanoMeta_talks.

NanoMeta2013 Day1

From today on, I have been in the conference NanoMeta2013 which is organized of European Physics Society. (it is quite interesting when I see the poster in front of the congress that the EPS is a 'Grass Root' organisation. the 'Grass Root', 草根 in Chinese, simply meaning ordinary people who do not claim superior power, etc. but gathering together can make an important influence on this society.)

The Conference is kicked off by a plenary talk by Uwe Kreibig on extensions of Mie theory due to Mie's incapability to explain many of the experiments in the area of nano-plasmonics. To Uwe, the field of 'plasmonics' is not new at all.  Many of the Mie's problem lie in the fact that Mie has adopted bulk permittivity of the material for the sphere, actually the spherical surface has a strong influence on the electronic response which can not be exactly described by the bulk. 
He is the author of a book:

Optical Properties of Metal Clusters. 

The section 'Quantum Plasmonics' in the morning leads to a strong debate on the methods of modelling sub-nm plasmonic gaps. The 'Quantum' plasmonics is mainly explaining the plasmonic effects by Quantum Mechanics. Classical electromagnetic theory by using bulk properties of materials will predict infinite field enhancement for a infinitesimal metallic tip, but from quantum physics, we can know this can not be true since the Pauli exclusion principle of the electrons. This is effect is need to take into consideration when tip/gap is below 1 nm. 

 Stephen Maier presented the non-locality theory for sub-nm tips. The non-locality theory is quite popular in recent years, and have been used in publications of F. Javier García de Abajo, D.R. Smith, S.A. Maier, et al.. The basic idea behind it is to introduce an 'electronic friction' in describing the collective oscillation of the electrons. 

Javier Aizpurua claims today that we should be cautious in applying the 'hydrodynamic' model of the electrons, since it has a failure history in describing previous surface physics, and will possibly result in the same consequence in describing closed surfaces- the area of plasmonics.  Javier and his collegues has developed an alternative method-- 'Time-dependent density functional theory', which originates from quantum theory.

I have expected more on Stephen Maier's presentation about broadband plasmonic antennas for SEIRS, but unfortunately he didn't go very deep into this part.

The talk of Frank Neubrech is quite nice as well.

Decay of dipole oscillation near planar interface

Details in the file link: Decay of dipole oscillation near planar interface

Mid-infrared Spectroscopy

As mentioned in a previous post on vibrational spectroscopy, one can use the infrared spectrum to determine the molecular structures, which may offer clues about the 'fingerprints' of the molecules. Compared to the weak vibrational overtone transitions which give rise to near infrared radiation, the mid-infrared gives much stronger signals that serves enough S/N ratio and works as the 'fingerprint' region of molecules. As an example, you can have a look at the absorption spectrum of Methane.

Absorption Spectrum of Methane

The biggest problem for laser spectroscopy in the mid-infrared is the lack of good laser sources in this spectrum range.

F.K. Tittel et al. has listed the available mid-infrared laser sources in the mid infrared in a book chapter, which is also given below:

Laser sources and their working range, courtesy[F.K. Tittel et al.]

Based on an excellent laser they developed in 2009, F. Adler et al. from JILA, Colorado has successfully developed a state-of-art mid-infrared laser spectroscopy. The work is excellent and the paper written is a classic to me, that's really worth to share with you in a summary of the paper in one short document: Google Drive--Mid-infrared Frequency comb Fourier Transform spectroscopy.

First Publication

My first publication related to my internship on Laser Speckle Contrast Analysis is now online, in which I perform the experiments and data analysis. 

Laser speckle analysis of flow in presence of static scatterers

I have introduced part of the project very briefly in a previous post on internship.

Mie Solution to sphere scattering

In the link below, you can find a short summary of J.A. Stratton's treatment on Sphere scattering in his classic book on 'Electromagnetic Theory'.

the notes--Mie solution of sphere scattering.

The very interesting part is the link between natural oscillation mode of the sphere, and the resonance condition upon plane wave incidence(which is the Mie's solution).
Hope you will enjoy it.