S U M M A R YWe calculate three dimensional (3-D) sensitivity kernels for fundamental-mode surface wave observables based on the single-scattering (Born) approximation. The sensitivity kernels for measured phases, amplitudes and arrival angles are formulated in the framework of surface wave mode summation. We derive kernels for cross-spectral multitaper measurements; as a special case, the results are applicable to single-taper measurements. Cross-branch modecoupling effects are fully accounted for in the kernels; however, these effects can probably be ignored at the present level of spatial resolution in global phase-delay tomography. The narrowly concentrated spectra of the windows and tapers commonly used in global surface wave studies enable the kernels to be computed extremely efficiently.Surface wave tomography based upon great-circle ray theory has been used with great success during the past three decades to constrain the large-scale 3-D heterogeneity of the lithosphere and upper mantle. While the growing abundance of seismic data promotes progress in retrieving better-resolved images with smaller-scale details, ray theory, upon which most surface wave tomography is based, has its theoretical limitations. Ray theory assumes that the frequency of seismic waves is infinite; thereby, it breaks down whenever the length scale of the heterogeneity is comparable to the characteristic wavelength of the seismic waves. Due to their finite frequency, surface waves are sensitive to 3-D structure off of the source-receiver great-circle ray. An approach beyond ray theory aiming at resolving small-scale structures is required to take into account the finite-frequency effects of surface waves. Recent studies have shown a growing appreciation of the finite-frequency properties of seismic body waves (

Using first principles calculations, we report for the first time that large nearly neutral aromatic molecules, such as naphthalene and anthracene, and small charge-transfer aromatic molecules, such as TCNQ and DDQ, interact more strongly with metallic single-wall carbon nanotubes (SWNTs) versus their semiconducting counterparts as the molecular orientation of DDQ is taken into account. Hence two new mechanisms for separating metallic and semiconducting SWNTs via noncovalent pi-pi stacking or charge-transfer interaction are suggested.