New publication on single-emitter two-photon-excited fluorescence

Our latest work on two-photon-excited fluorescence of single quantum dots is now published in ACS Photonics!

Individual gold nanorods are used to enhance the fluorescence emission of a single quantum dot when it is excited by the absorption of two low energy photons.

In a nutshell, we showed more than 10000-fold enhanced fluorescence of a single semiconductor quantum dot using a two-photon-excitation scheme. The high enhancement of this nonlinear effect arises mainly from the local field amplification at the tip of the nanorod. For more details, see the paper.

Congratulations to all the authors!

New publication in Nano Letters

We are proud of our research! Our latest publication on nanothermometry is in the top-10 most-read NanoLetters papers of the month!

(left) Anti-Stokes emission spectra of an individual gold nanorod excited in resonance with different laser powers. The lines are fits using our model. (right) Extracted temperature of the nanorod for several excitation powers.

Briefly, in this paper we present a method to extract the absolute temperature of an individual gold nanorod by measuring the anti-Stokes emission spectra. We present a simple model to interpret the data and we show that we can achieve 4K accuracy in the temperature determination with only 180s integration time.

Congratulations to the authors!


NGL lecture by Michel Orrit

On 18 January 2018, Michel Orrit will give a lecture as part of the NGL lecture series (Natuurwetenschappelijk Gezelschap Leiden)

Single molecules and single gold nanoparticles in the spotlight

Michel Orrit will present several optical methods giving access to signals from single molecules and single gold nanoparticles. Single gold nanoparticles are interesting because of their strong interaction with light mediated by their plasmon resonance, and because they are chemically and photochemically very stable. The experiments are based on fluorescence or photoluminescence, scattering, absorption detected by photothermal contrast, purely refractive effects leading to shifts of the plasmon resonance, or plasmon-enhanced fluorescence of weak emitters. Some chosen results will demonstrate the power of these experiments to explore the nanoworld in a non-invasive way.


De Sitterzaal
Huygens Laboratory
Leiden University
Niels Bohrweg 2
2333 CA Leiden


19:30 lecture hall open
19:45 lecture
20:30 break
20:45 continuation of the lecture
21:15 End

Registration form
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Spinoza Prize awarded to Michel Orrit

2017 Spinoza prize winners – left-to-right: Alexander van Oudenaarden, Eveline Crone, Albert Heck en Michel Orrit (photo: NWO/Ivar Pel)

On 16 June 2017, the Netherlands Organisation for Scientific Research NWO announced that Professor Michel Orrit is among the winners of this year’s Spinoza prize.

The Spinoza Prize is the highest Dutch scientific award, and comes with a grant of 2.5 million euro to be spent on further scientific research. This high honour was awarded to Prof. Orrit in recognition of his seminal work in the field of single-molecule spectroscopy.

Congratulations, Dr Carattino!

Congratulations to Dr Aquiles Carattino, who successfully defended his PhD thesis titled “Gold Nanorod Photoluminescence — Applications to Imaging and Temperature Sensing” on Thursday 9 March 2017 at Leiden University’s Academy Building in the traditional manner.

Aquiles Carattino (ctr), flanked by his paranymphs Martín Caldarola (l) and Pravin Kumar (r)

New publication on single-molecule electrochemistry

We are proud of our recent publication on single-molecule electrochemistry using enhanced fluorescence as readout.

At both ends of the nanorod (yellow), the incoming electromagnetic field of light is amplified by a factor 300 (red spots). If a molecule (blue dots) is situated there, its fluorescent signal is gets 500 times stronger.

We used gold nanorods as nanoatennas to reveal single-molecules of a redox sensitive dye, Methylene Blue, and studied the electrochemical properties of this molecule one by one.

Leiden University’s Press release can be found here and a comment at here

Publication: M.Sc. Weichun Zhang, Dr. Martín Caldarola, M.Sc. Biswajit Pradhan, Prof.?Dr. Michel Orrit, ‘Gold Nanorod-Enhanced Fluorescence Enables Single-Molecule Electrochemistry of Methylene Blue‘, Angewandte Chemie

Michel Orrit wins Edison Volta Prize

The European Physical Society (EPS) has awarded the prestigious Edison Volta Prize to Professor Michel Orrit. The prize, which is awarded annually by the EPS “to promote excellent research and achievement in physics”, was awarded to Orrit

for “seminal contributions to optical science, to the field of single-molecule spectroscopy and imaging (first single molecule detection by fluorescence and first optical detection of magnetic resonance in single molecule) and for pioneering investigations into the photoblinking and photobleaching behaviors of individual molecules at the heart of many current optical super-resolution experiments.”

Edison Volta Prize

Within the past year, Michel Orrit has also been awarded the Physica Prize by the Dutch Stichting Physica and the Nederlandse Natuurkundige Vereniging as well as the Grand Prix Léon Brillouin by the Société Française d’Optique.

Read the announcement on the website of the Leiden Institute of Physics.

Michel Orrit wins the Physica Prize 2016

The Nederlandse Natuurkundige Vereniging and Stichting Physica have announced that Michel Orrit will receive the national Physica Prize 2016. Michel Orrit is honoured with the prize for his groundbreaking work on single molecule spectroscopy. In the mid ‘80s, Orrit came to the realization that it should be possible to optically detect a single molecule. A few years later, in 1990, he indeed became the first one to detect the fluorescence signal of one molecule.

Last year, the Nobel Prize in Chemistry was awarded to Betzig, Hell and Moerner for the development of super-resolved fluorescence microscopy. The Nobel Committee’s description of the scientific background clearly showed the groundbreaking significance of Orrit’s experiment as the basis for the super-resolution techniques that were established afterwards. Moerner measured a single molecule slightly before Orrit, using absorption, but Orrit’s measurement using fluorescence produced much less background noise and became the standard in this scientific field.

Michel Orrit wins Physica Prize

Faster computers with a GPS for electrons?

To build faster computers and larger memories physicists need to know the exact position of electrons in microcircuits. Prof. Michel Orrit and colleagues want to build an apparatus for that, with the help of a 0.5 MEuro investment from the Stichting Fundamenteel Onderzoek der Materie (FOM).

Electronic GPS: simultaneous measurement of several electrons:

Prof dr Michel Orrit and Dr Sanli Faez, in collaboration with Dr Sense Jan van der Molen, have proposed a new platform to detect the charge distribution at the nanoscale. They even expect to be able to detect elementary particles, electrons, simulataneously, which is not possible with scanning probe techniques.

Schematic principle of the technique

Organic dye molecules are immobilized over a network of gold nanoparticles. Charging and discharging of hte particles modifies electric fields, thereby shifting the resonance frequency (color) of individual molecules. These frequencies are read with high accuracy through high-resolution laser spectroscopy.

Nanometer resolution

Instead of a single large reading device, the team will use a number of organic molecules as independent nanodetectors. They can be placed on top of a chip with gold nanoparticles and used to map the charge distribution of the chip. This is made possible by the large sensitivity of the molecular optical transition to spectral shifts caused by electric fields stemming from individual charges in the molecule’s environment. The resolution expected should be around a nanometer.

Faster computers

Orrit: “Our experiment can be useful to devise new methods for information storage and transfer, and to analyze scales smaller than current semiconductor transistors. This can in turn lead to faster computers with a larger storage capacity. It will help researchers get new insights into the physics of electronic components at such small scales.

About the grant

Projectruimte proposals of FOM funds small-scale fundamental projects with an innovative character and with a clear scientific, industrial or societal relevance. FOM had a budget of 10 million Euro for 2015, from which 3 million were earmarked for projects within the Sectorplan Physics and Chemistry.