# Quantum mechanics boosts photosynthesis - …

This reaction, however, has a large activation barrier and thus at ultracold temperatures there is a very low probability that OH and H_{2} react via thermal activation. Experiments running under simulated conditions of dark clouds revealed that the efficiency of this reaction is highly influenced by isotope effects. This means that using molecular deuterium (D_{2}) instead of H_{2 }reduces the efficiency of the discussed reaction by about one order of magnitude []. Such observations point to quantum tunnelling due to the strong dependence of the tunnelling rate on the particle mass. Other relevant reaction pathways for the synthesis of solid H_{2}O in dark clouds such as the hydrogen peroxide pathway also depend on quantum tunnelling in order to circumvent the low probability of overbarrier reactions []. This shows that quantum tunnelling is of high importance for the formation of H_{2}O within dark clouds.

## Research News: Quantum Secrets of Photosynthesis …

### Quantum Secrets of Photosynthesis Revealed: ..

*Any oscillation can be described as a sum of sinusoidal oscillations of increasing frequency, called Fourier modes; sideways oscillations can be described by the temporal Fourier modes of tangent angles. Power-spectrum analysis showed that experimentally observed oscillations in tangent angles were well approximated using only the first (fundamental) Fourier mode, so the sperm equation could be analytically solved using values of this mode. Tangent angles quantify the curvature of the axoneme at a given position, and the curvature is geometrically related to the sliding distance between doublets at that position. The sperm equation thus relates time-dependent angular movement at each position to the extent and rate of inter-doublet sliding at that position, and to the local forces that either oppose or promote further sliding. The model contains two adjustable parameters – stiffness and friction of the active material inside the axoneme that deforms and exerts force during bending. It also contains several fixed parameters that J�licher and colleagues independently measured and fed into the equation. These include the hydrodynamic drag of the moving flagellum and its ordinary stiffness, both of which oppose active deformation, and the beat frequency. The authors obtained an excellent fit to the data, with both internal stiffness and friction taking the negative values expected for an active material. Importantly, a microscopic model of dynein behaviour, incorporating the force-dependent detachment concept illustrated in Figure 2, predicted negative values for stiffness and friction similar to those obtained by fitting the sperm equation.*

### Quantized vibrations are essential to photosynthesis, …

The central characteristic of quantum tunnelling is the fact that under certain conditions elementary particles, nucleons or atoms are able to negotiate the obstacle of a potential barrier (which is, from the classical point of view, a forbidden area for a particle) without having the energy to overcome it. The STM setup gives an illustrative example of potential barrier width: the nanometre-wide gap between the tip and the sample. The benefit of creating such a gap becomes clear when considering the nature of quantum tunnelling.