Rotational spectrum of molecular ion NH^+ as a probe for alpha- and m_e/m_p-variation

Microwave and submillimeter molecular transitions and their dependence on fundamental constants

Microwave and submillimeter molecular transition frequencies between nearly degenerated rotational levels, tunneling transitions, and mixed tunneling-rotational transitions show an extremely high sensitivity to the values of the fine-structure constant, alpha, and the electron-to-proton mass ratio, mu. This review summarizes the theoretical background on quantum-mechanical calculations of the sensitivity coefficients of such transitions to tiny changes in alpha and mu for a number of molecules which are usually observed in Galactic and extragalactic sources, and discusses the possibility of te…

甲醇中的扭转-转动跃迁作为基本物理常数——电子和质子质量——的探针

Torsion-rotational transitions in methanol as a probe of fundamental physical constants -- electron and proton masses

该研究利用朝 Orion-KL 观测到的 CH3OH 与 (13)CH3OH 微波扭转-转动发射线，以两种独立方式约束电子-质子质量比 μ 的变化，得到 Δμ/μ < 1.1×10^-8（1σ）。

利用单离子探针观测空间相关的旋转多普勒频移

Observation of Space-Dependent Rotational Doppler Shifts with a Single Ion Probe

提出用单个被囚禁离子探测两束共轴涡旋激光的旋转多普勒效应，通过空间定位、模拟与解析模型揭示其随靠近光束中心增强且与束腰无关。

Comment on "21-cm Radiation: A New Probe of Variation in the Fine-Structure Constant"

Khatri and Wandelt reported that change in the value of alpha by 1% changes the mean brightness temperature $T_b$ decrement of the CMB due to 21 cm absorption by 5% over the redshift range z $<$ 50. A drawback of their approach is that the dimensionful parameters are used. Changing of units leads to the change of the magnitude and even sign of the effect. Similar problems may be identified in a large number of other publications which consider limits on the variation of alpha using dimentionful parameters. We propose a method to obtain consistent results and provide an estimate of the effect.

Sensitivity of Tunneling-Rotational Transitions in Ethylene Glycol to Variation of Electron-to-Proton Mass Ratio

Ethylene glycol in its ground conformation has tunneling transition with the frequency about 7 GHz. This leads to a rather complicated tunneling-rotational spectrum. Because tunneling and rotational energies have different dependence on the electron-to-proton mass ratio $μ$, this spectrum is highly sensitive to the possible $μ$ variation. We used simple 14 parameter effective Hamiltonian to calculate dimensionless sensitivity coefficients $Q_μ$ of the tunneling-rotational transitions and found that they lie in the range from $-17$ to $+18$. Ethylene glycol has been detected in the interstellar…

Reconstruction of a Rotational Wavepacket of Inverted Molecular Ions in an Intense Femtosecond Laser Field

We report on generation of a rotational wavepacket in the ground vibronic state (v = 0) of excited electronic B2Σu+ state of N2+ in a femtosecond laser induced plasma spark. Decoding of the rotational wavepacket is achieved with the frequency-resolved seed-amplified air laser spectrum resulting from the population inversion between the B2Σu+-X2Σg+ states of N2+ in the plasma. We also observe that the rotational wave-packet leads to modulation of the amplified seed signals in the time domain using a pump-probe scheme, which can be well reproduced by theoretical calculation. Our results demonstr…