Nanojoule Adsorption Calorimetry. Design, Construction, Novel Evaluation Approach, Software Development, Characterization, and Exemplary Measurements

The interaction of single molecules with surfaces as well as the interaction between surfaces, i.e., interfaces, are often of great interest and thus a vast field of applied sciences arises therefrom. Most ultra high vacuum based surface science techniques are only able to deliver information about an already formed interface. The desire for knowledge of the energetics describing the processes during the formation of such a contact layer motivates the usage of nanojoule adsorption calorimetry. This work presents the construction of the experimental setup necessary to study the coverage dependent heat of adsorption. The setup is optimized for investigations involving the adsorption of metal atoms on organic thin films and of large organic molecules on surfaces of single crystalline metals. The software developed for this work and used for data treatment is also covered by this thesis. In this respect, the user interface as well as the program code processing the data are both well discussed. The characterization of the components involved in calorimetric experiments is presented in detail later in this work. Finally, selected experiments involving the adsorption of magnesium, zinc, copper, and calcium on the pristine and cleaned detector surface as well as on 3,4,9,10-perylene-tetracarboxylic dianhydride, tetraphenylporphyrin, alpha-sexithiophene, and poly(3-hexylthiophene) are exemplarily discussed. This paper is completed by design drawings of the constructed elements for this work, the source code of the data treatment program developed for this work, an overview of the investigated systems, and the parameters used to operate the scientific equipment. Considering all individual aspects presented in this dissertation conjoined, the scientific framework necessary to study coverage dependent heats of adsorption precisely is established

Multiplicity of different hadrons in e+e−e^{+}e^{-}, pp, and AA collisions

Employing the recently developed neXus model, we compare the yields of different hadrons in ultra-relativistic collisions: electron-positron annihilation at 91 GeV, proton-proton scattering at 17 GeV and nucleus-nucleus collisions at 17 GeV (SPS) and 200 GeV (RHIC). Plotting the yields as a function of the hadron masses, we find very surprising results: we observe that the spectra are practically identical for e+e- at 91 GeV and central nucleus-nucleus reactions at SPS and RHIC energies, whereas the spectrum for proton-proton scattering is somewhat steeper. All have the form one expects if the particles were emitted by a canonical system which is characterized by a temperature and chemical potentials. These identical forms have, however, different origins: in e+e- and pp the exponential shape it is due to the statistical behavior of string fragmentation, which has absolutely nothing to do with thermalization, in AA it is caused by phase space. The fact that e+e- and nuclear results agree is pure coincidence. Surprisingly the results for pp and e+e- differ, although here the production mechanism is identical. In pp collisions we see directly that the string energy is very limited and hence the high mass baryons are suppressed. We conclude that it is practically impossible to draw conclusions from hadronic yields about the reaction mechanism

Multi-strange Baryon Production from Identical Pomerons in Proton Proton Collisions

The recent data on pp collisions at 158GeV provide severe constraints on string models: These measurements allow for the first time to determine how color strings are formed in ultrarelativistic proton-proton collisions

Molecular quantum spin network controlled by a single qubit

Scalable quantum technologies will require an unprecedented combination of precision and complexity for designing stable structures of well-controllable quantum systems. It is a challenging task to find a suitable elementary building block, of which a quantum network can be comprised in a scalable way. Here we present the working principle of such a basic unit, engineered using molecular chemistry, whose control and readout are executed using a nitrogen vacancy (NV) center in diamond. The basic unit we investigate is a synthetic polyproline with electron spins localized on attached molecular sidegroups separated by a few nanometers. We demonstrate the readout and coherent manipulation of very few ($\leq 6$) of these $S=1/2$ electronic spin systems and access their direct dipolar coupling tensor. Our results show, that it is feasible to use spin-labeled peptides as a resource for a molecular-qubit based network, while at the same time providing simple optical readout of single quantum states through NV-magnetometry. This work lays the foundation for building arbitrary quantum networks using well-established chemistry methods, which has many applications ranging from mapping distances in single molecules to quantum information processing.Comment: Author name typ

Strangeness Suppression in Proton-Proton Collisions

We analyse strangeness production in proton-proton (pp) collisions at SPS and RHIC energies, using the recently advanced NeXus approach. After having verified that the model reproduces well the existing data, we interpret the results: strangeness is suppressed in proton-proton collisions at SPS energy as compared to electron-positron (e+e-) annihilation due to the limited masses of the strings produced in the reaction, whereas high energy pp and e+e- collisions agree quantitatively . Thus strangeness suppression at SPS energies is a consequence of the limited phase-space available in string fragmentation.Comment: 7 Figures, 4 Page

Cosmic Rays from the Knee to the Highest Energies

This review summarizes recent developments in the understanding of high-energy cosmic rays. It focuses on galactic and presumably extragalactic particles in the energy range from the knee (10^15 eV) up to the highest energies observed (>10^20 eV). Emphasis is put on observational results, their interpretation, and the global picture of cosmic rays that has emerged during the last decade.Comment: Invited review, submitted to Progress in Particle and Nuclear Physic

FGF-21 levels in polyuria-polydipsia syndrome

The pathomechanism of primary polydipsia is poorly understood. Recent animal data reported a connection between fibroblast growth factor 21 (FGF-21) and elevated fluid intake independently of hormonal control by the hormone arginine-vasopressin (AVP) and osmotic stimulation. We therefore compared circulating FGF-21 levels in patients with primary polydipsia to patients with AVP deficiency (central diabetes insipidus) and healthy volunteers. In this prospective cohort study, we analyzed FGF-21 levels of 20 patients with primary polydipsia, 20 patients with central diabetes insipidus and 20 healthy volunteers before and after stimulation with hypertonic saline infusion targeting a plasma sodium level >= 150 mmol/L. The primary outcome was the difference in FGF-21 levels between the three groups. Baseline characteristics were similar between the groups except for patients with central diabetes insipidus being heavier. There was no difference in baseline FGF-21 levels between patients with primary polydipsia and healthy volunteers (122 pg/mL (52,277) vs 193 pg/mL (48,301), but higher levels in patients with central diabetes insipidus were observed (306 pg/mL (114,484);P=0.037). However, this was not confirmed in a multivariate linear regression analysis after adjusting for age, sex, BMI and smoking status. Osmotic stimulation did not affect FGF-21 levels in either group (difference to baseline: primary polydipsia -23 pg/mL (-43, 22);central diabetes insipidus 17 pg/mL (-76, 88);healthy volunteers -6 pg/mL (-68, 22);P=0.45). To conclude, FGF-21 levels are not increased in patients with primary polydipsia as compared to central diabetes insipidus or healthy volunteers. FGF-21 therefore does not seem to be causal of elevated fluid intake in these patients