Winners announced for the Cavendish Photography Competition 2023-24

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Phase two, Phase Blue

A particular strength of the Cavendish has been the ability of its researchers to adapt and evolve to stay at the forefront of cutting-edge science across its rich history. Time and time again Cavendish researchers have shown the importance of transcending traditional labels through diverse interdisciplinary collaborations to solve modern research problems. 

A prominent example is research into Organic Light Emitting Diodes (OLEDs), which has been the source of cooperation between Cambridge Physicists and Chemists since they reported the first polymer OLED in 1990. Over thirty years later the quest for a stable and efficient blue OLED remains as a challenging research problem, in which Cavendish Physicists and Yusuf Hamied Department of Chemistry Chemists are still working together at the forefront, highlighted by a recent report on a ground-breaking blue emissive molecule that allows the device structure of blue OLEDs to be substantially simplified:

Suppression of Dexter transfer by covalent encapsulation for efficient matrix-free narrowband deep blue hyperfluorescent OLEDs, H.-H. Cho, D. G. Congrave, N. C. Greenham and H. Bronstein et al. Nature Materials (2024). https://doi.org/10.1038/s41563-024-01812-4

The photograph shows two immiscible solvents with nearly equal densities. One is water and the other is an organic solvent containing the new blue emissive molecule developed in Cambridge. The two liquids separate into fine bubbles when agitated and show deep blue emission under UV light. The same emission is generated electronically in OLED devices. The two phases in this photograph serve as a metaphor for interdisciplinary research at the Cavendish - while they can often be thought of and taught as separate branches of science, when combined in an interdisciplinary fashion, Chemistry and Physics can yield a result more beautiful than the sum of its parts.

Special mention for Craig Yu and Stephanie Montanaro who helped with the photograph. 

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The nano-garden of a scientist

Research on (semi)conducting materials and devices at the Cavendish Laboratory can be traced back to the middle of the 19th century. Sir Nevill Francis Mott, FRS, Cavendish Professor of Physics, won the Nobel Prize for Physics in 1977 for his work on the electronic structure of magnetic and disordered systems, especially amorphous semiconductors. Today the research on (semi)conducting materials and devices at the Cavendish Laboratory has influences beyond Cambridge and continues to result in world-leading achievements.

As the performance and processing of Si-based electronic materials and devices reach fundamental limits, the exploration of new materials is an engine of progress in performance and novel applications. Two-dimensional (2D) conjugated coordination polymers (cCPs) represent an emerging class of materials with rich chemistry and physics and have demonstrated great potential in supercapacitor, electronic, thermoelectric and spintronic applications. These 2D cCPs with specific physical and chemical properties can be prepared in a controlled, mild manner by tailored design and precise synthesis. The main challenge is to control the orientation and the growth along the most efficient, delocalized charge transport direction, which is difficult because of the very different growth dynamics between the in-plane metal-coordination bonds and the cross-plane Van der Waals and π-π interactions. In this work, we unravel the growth evolution of 2D cCPs films in liquid-liquid interfacial synthesis at the nano-/micro-scale at different growth stages and under the influence of different factors. Surprisingly, we find that in some cases, depending on the conditions, the cross-sectional electron microscopy images of the films exhibit irregular structures appearing like plants and flowers at the nano- or submicro-scale. We are interested in understanding the correlation between the microstructure of these films and their charge and heat transport physics and thermoelectric properties. The improved understanding in the preparation of this new class of materials will provide a research platform for observing new scientific phenomena, expanding fundamental chemical and physical knowledge, and benefitting a broad range of future advanced applications in (bio)electronics, energy storage, thermoelectrics and spintronics eventually.

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The Colors of Fabrication

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150 years ago, the Cavendish Laboratory became one of the first prominent hubs of experimental physics in the world, promoting the idea that experiment, along with theory, is vital to the study of physics. Since then, Cavendish professors such as JJ Thomson and Nevill Mott have performed groundbreaking experiments that drastically changed physics theory. For example, Thomson's discovery of the electron revolutionized how we describe atoms and particles, and without his experimental discoveries, the theoretical backbone of fields like quantum mechanics and semiconductor physics would fail to exist. The presented microscope image, The Colors of Fabrication, relates to this idea of learning through experiment; the image shows the edge of a semiconductor wafer during a novel device fabrication process to make gallium arsenide solar cells on glass. By drawing on semiconductor physics theory, we can predict how electrons move throughout this structure, but to verify these predictions, we must perform experiments and measure actual solar cell devices. Sometimes, the theory agrees, but sometimes, we must revise our theory based on our observations, creating an iterative process that is at the heart of the scientific method. Just as 150 years of Cavendish Laboratory researchers have done before us, we will continue the legacy of expanding our knowledge of theory through experimentation.

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Connected cells and connected researchers

This fluorescence image shows the expression of carbonic anhydrase IX (CAIX) in the kidney cancer cell line A704; CAXI is a transmembrane protein whose over-expression is linked to the VHL mutation in clear cell renal cell carcinoma, the most common type of kidney cancer.

The fluorescent labelling of the CAIX protein present in these cells allows us to see the many micro-tubule connections between the cells in stunning detail. It reveals how each cell forms many connections to its neighbours in order to survive by sharing nutrients and signalling molecules, as well as allowing the cells to co-ordinate their activities to achieve functional tissues and organs. This bears a striking resemblance to the behaviours and needs of researchers at the Cavendish. Just like these mammalian cells in 2D culture, connected and supported researchers are able to excel by sharing resources, knowledge and co-ordinating their efforts towards the united goal of advancing scientific research.

The brightness and contrast of this image have been altered to enhance the visibility of the micro-tubule connections. Until the creation of the Cavendish Laboratory, physics was widely regarded as a branch of mathematics, with only theoretical physics being supported by the physics department at Cambridge. The launch of the Cavendish led to the building of the very first experimental physics laboratories in Cambridge; this vision of growth has continued over the illustrious 150 year history of the Cavendish, resulting in a flourishing Physics of Medicine sub-department which has facilitated this research.

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In 1995, the first exoplanet orbiting a ‘solar-like’ star was discovered!

The planet, 51 Pegasi b, is known as a ‘Hot-Jupiter’; a planet unlike those in our solar system, its size is comparable to that of Jupiter but it orbits much closer to its host star.

This pioneering work kick-started the exoplanet field as we know it today and, in 2019, led to the awarding of the Nobel Prize to Prof. Didier Queloz of the Cavendish Astrophysics group (as of 2012).

The discovery of 51 Peg b, was made using the radial-velocity technique. As a planet orbits its host star, it brings about tiny changes in the colour of the starlight through the Doppler effect. Using instruments called stabilised spectrographs, we can accurately measure these changes; leading to the discovery and characterisation of new planets.

In the three decades since that pioneering discovery, a fraction of the 150 years the Cavendish has seen, the field of exoplanets has flourished and matured immensely. Now, with over 5,500 exoplanets discovered to date, a wealth of knowledge on the structure and occurrence of these planetary systems has been acquired.

Despite this great success, an Earth “twin” is yet to be discovered. The challenge in discovering ‘another Earth’ comes both from the technical difficulty in reaching a sufficiently high level of precision in our instrumentation but also from additional ‘noise’ in our measurements coming from variability of the exoplanet’s host star.

Fortunately, in addition to the field of exoplanets as a whole maturing, so has the radial-velocity technique. Now, there are ‘extreme precision radial velocity’ instruments able to achieve the precision required to detect Earth analogues.

However, this still leaves the ‘stellar noise’ from the exoplanets host star in the way of ‘Earth-twin’ discoveries.

This is where the Cavendish-led Terra Hunting Experiment comes in. The Terra Hunting Experiment will conduct the most intensive series of radial velocity observations to date, taking ‘nightly’ measurements of sun-like stars in the stellar neighbourhood over the period of a decade with the goal to mitigate the ‘stellar noise’ and discover ‘Earth-like’ planets orbiting around ‘Sun-like’ stars.

To undertake this, an extreme precision radial velocity stabilised spectrograph, ‘HARPS3’, is being assembled at the Cavendish Laboratory and soon, in early 2025, it will be coupled to the 2.54m diameter Isaac Newton Telescope (INT) on the island of La Palma; beginning the decade long hunt.

Like the Cavendish, the INT has a long history too. Originally inaugurated in 1967 in Sussex, England; where, at the time, its 2.54m diameter was amongst the largest in the world. It was later upgraded and moved to La Palma in 1984; where better observing conditions allowed the most to be made of this grand telescope.

In the 40 years since then, many of the telescope’s systems had become obsolete and were breaking down, with spare parts difficult to source. It’s understood that eventually, unless something substantial was done, this could have slowly meant the end for the INT.

Happily though, the Terra Hunting Experiment is seeing the INT completely refurbished and roboticised, making it robust enough to undertake this intensive search for ‘Earth-twins’ and giving it life for decades to come.

Hence, with HARPS3 given life and the INT being given new life once again, they will use this life to search for new worlds …and who knows, these worlds may even be capable of hosting new life.

Photo details:

This image was taken in a single 30sec exposure from the dome of the Isaac Newton Telescope looking out over the stars that the telescope will soon be surveying for Earth-like planets orbiting around Sun-like stars.

The photo was shot over the summer of 2023 during an inspection visit to La Palma as a part of the refurbishment of the Isaac Newton Telescope. The silhouette of the telescope seen in this image is the Jacobus Kapteyn Telescope (JKT); the INT’s neighbour.

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Maxwell

In 1861, thirteen years before the Cavendish was established, James Clerk Maxwell unveiled the first colour photograph. It was a crude image of a tartan ribbon created by compositing three images taken with red, green and blue filters and tinting them to provide full colour. Due to the process having low sensitivity to red and green light the result was muted, but it showed for the first time an accessible window into colour theory and electromagnetism.

Since then a lot has changed. Maxwell came to Cambridge to establish the Cavendish Laboratory. The electron was discovered, the atom was split and pulsars were observed. What has remained throughout is the drive to find the groundbreaking and share it with the world.

In the Optofluidics group based in the Maxwell Centre, we use hollow-core photonic crystal fibre waveguides to undertake novel liquid sensing with applications in photocatalysis, battery chemistry and biophysics. Using Maxwell’s contributions to electromagnetism as a foundation, further developments from the Cavendish have contributed to our work. Rayleigh’s observations of photonic crystals are fundamental for the basis of hollow-core photonic crystal fibres and the theory behind Bragg reflections provide explanation for the guidance mechanisms of the fibres. This all ties together to allow us to investigate novel photocatalysts to help find the next step in green photocatalysis, probe Li-ion batteries in-operando to understand battery degradation and even biophysical sensing of viruses with applications in pharmacology.

To celebrate 150 years since the Cavendish’s foundation, we looked to research being actively carried out in our group and incorporating Maxwell’s photographic techniques. Maxwell is a trichromatic picture of the building produced using Maxwell’s colour photography technique. Black and white photographic film was used to take three individual pictures with red, green and blue filters which were subsequently tinted and stacked digitally to produce a colour image.

By using the trichromatic photographic technique, we look at the heritage of the institution’s origins and apply it to the work that pushes the Cavendish into the future.

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Order from Disorder

‘Order from Disorder’ pays homage to the legacy of pioneering research that has characterized Cavendish Laboratory for a century and a half.  It was here where the seed of atomic theory was sown that later grew into the oak of quantum mechanics, a journey marked by numerous eminent figures such as Phil Anderson, whose insights into symmetry breaking and emergent phenomena now underpin our exploration of many-body quantum states.

‘Order from Disorder’ unveils the part of an intricate setup, to cool atoms down to ultracold temperatures, a precursor for creating interesting many-body quantum state.  Under this seemingly chaotic web of laser beams on an optical table, lies the promise of extreme order of the atomic states.  This allows us to peek through the atomic ballet, where extreme order emerges from this apparent disordered yet choreographed arrangement of optical elements.